Answer:
b. private producers of such goods will have little incentive to control costs and provide them at low prices
Explanation:
Externality is a situation where the production activities of market participants (either producers or consumers) have an effect on third parties not involved in production.
Externality is a form of market inefficiency.
Negative externality is when goods are produced privately, but the cost of their purchase is paid for by the taxpayer or some other third party.
When negative externality occurs, producers have little incentive to reduce cost because they don't bear the total brunt of their activities. This is why activities that generate negative externality are over produced.
Government needs to step in to control this problem. They can either impose tax on producers or regulate their activities.
Pollution is an example of negative externality.
I hope my answer helps you