Which statement best describes why externalities are not efficiently resolved by a competitive market?

Which statement best describes why externalities are not efficiently resolved by a competitive market?

• A. Market transactions do not account for external costs or benefits affecting third parties.
• B. Externalities are private costs.
• C. Prices always reflect true costs.
• D. Public goods fix the problem.

Answer: (A)

Externalities occur when the costs or benefits of a transaction spill over to people who are not directly involved. In a competitive market, buyers and sellers face only their private costs and benefits, so prices don’t reflect the extra costs or benefits borne by others. That mismatch means the market tends to allocate resources inefficiently: harmful activities may be overproduced and beneficial ones underproduced because the social impact isn’t included in the price. For example, pollution from a factory imposes costs on others that the factory doesn’t pay for, leading to too much pollution. Conversely, education or vaccination yields social benefits that individuals may not fully value in their own decisions, so less is produced than is socially optimal. The other statements aren’t correct because externalities are not private costs, prices don’t always reflect true costs, and public goods are a separate issue with a different mechanism for addressing efficiency.

Externalities occur when the costs or benefits of a transaction spill over to people who are not directly involved. In a competitive market, buyers and sellers face only their private costs and benefits, so prices don’t reflect the extra costs or benefits borne by others. That mismatch means the market tends to allocate resources inefficiently: harmful activities may be overproduced and beneficial ones underproduced because the social impact isn’t included in the price.

For example, pollution from a factory imposes costs on others that the factory doesn’t pay for, leading to too much pollution. Conversely, education or vaccination yields social benefits that individuals may not fully value in their own decisions, so less is produced than is socially optimal. The other statements aren’t correct because externalities are not private costs, prices don’t always reflect true costs, and public goods are a separate issue with a different mechanism for addressing efficiency.