Correct answer: A

The correct answer is A cost imposed on third parties who are not part of a transaction.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Pollution is a common negative externality because market participants may not bear the full social cost.
3. Connect choice and tradeoffs: The correct answer is A cost imposed on third parties who are not part of a transaction.

Correct answer: B

The correct answer is A good that is generally nonexcludable and nonrival in consumption.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: National defense is a standard example because people cannot easily be excluded and one person's protection does not reduce another's.
3. Connect choice and tradeoffs: The correct answer is A good that is generally nonexcludable and nonrival in consumption.

Correct answer: C

The correct answer is A resource that is difficult to exclude people from using but can be depleted.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Fisheries, grazing land, and some groundwater supplies can face overuse because access is difficult to restrict.
3. Connect choice and tradeoffs: The correct answer is A resource that is difficult to exclude people from using but can be depleted.

Correct answer: D

The correct answer is How the burden of a tax is divided between buyers and sellers.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Economic incidence depends on relative elasticities, not simply on which side of the market legally sends the tax payment.
3. Connect choice and tradeoffs: The correct answer is How the burden of a tax is divided between buyers and sellers.

Correct answer: A

The correct answer is A tax for which the average tax rate rises as income rises.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Progressive taxes place a larger share of income on higher-income taxpayers, under the relevant tax schedule.
3. Connect choice and tradeoffs: The correct answer is A tax for which the average tax rate rises as income rises.

Correct answer: B

The correct answer is Government decisions about spending, taxation, and borrowing.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Fiscal policy can influence aggregate demand, distribution, public services, and economic stabilization.
3. Connect choice and tradeoffs: The correct answer is Government decisions about spending, taxation, and borrowing.

Correct answer: C

The correct answer is A situation in which an unregulated market allocation is inefficient or does not reflect social costs and benefits.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Externalities, public goods, information problems, and market power can cause private decisions to diverge from socially efficient outcomes.
3. Connect choice and tradeoffs: The correct answer is A situation in which an unregulated market allocation is inefficient or does not reflect social costs and benefits.

Correct answer: D

The correct answer is Limit harmful activities or require standards that protect health and natural systems.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Regulation can address external costs through emissions limits, technology standards, monitoring, and enforcement.
3. Connect choice and tradeoffs: The correct answer is Limit harmful activities or require standards that protect health and natural systems.

Correct answer: A

The correct answer is Comparing expected social benefits with expected social costs of an action.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Cost-benefit analysis helps compare alternatives, though estimates can involve uncertainty and difficult value judgments.
3. Connect choice and tradeoffs: The correct answer is Comparing expected social benefits with expected social costs of an action.

Correct answer: B

The correct answer is Rules change incentives and behavior, sometimes creating new costs or distortions.

1. Identify the economics concept: Determine whether the question concerns scarcity, incentives, markets, production, labor, public policy, international trade, or economic indicators.
2. Apply the economic model: Policies can alter supply, demand, avoidance behavior, innovation, enforcement costs, and distribution in unexpected ways.
3. Connect choice and tradeoffs: The correct answer is Rules change incentives and behavior, sometimes creating new costs or distortions.