Which program is an example of domestic policy?

a.) nafta
b.) the versailles treaty
c.) the carter doctrine
d.) the clean air act
e.) nato

The correct answer is D.) The Clean Air Act 

It is domestic because it only applies to the USA, that is, it's a federal law. NATO and the Carter Doctrine are military alliances and endeavors, the Versailles Treaty was a peace convention for numerous countries, and NAFTA is a trade agreement.

It is c because it shows how the author is stating their own oppinion about the protagonist