...talking, she says to you...? "The government should not provide national defense because the free market can do an efficient job of providing that service."

The best response that shows your knowledge of economics is:

A.Yes, you are right, because the market never fails.
B. No, you are wrong, because national defense is a public good and people could enjoy the benefits of national security without paying for it.
C.Yes, you are right, because everyone will see the necessity of national defense and pay for it.