Which of the following is a classic example of a positive externality?

• A. Bees pollinating crops
• B. Air pollution from a factory
• C. Traffic congestion
• D. Noise from a construction site

Answer: (A)

A positive externality happens when the action of one party creates benefits for others who don’t pay for it. Bees pollinating crops is a classic example because the pollination helps crops yield more fruit and better quality, delivering benefits to farmers and even to consumers beyond any payment to the bees or beekeepers. Those extra benefits spill over without a corresponding charge, which is the hallmark of a positive externality. The other options involve costs or nuisances imposed on others—air pollution harms health and the environment, traffic congestion delays other drivers, and construction noise disturbs people—so they illustrate negative externalities rather than positive ones.