The Goal of Public Economics,or Public Finance,is to Answer Which

The goal of public economics,or public finance,is to answer which question?

A) How might the government intervene in the economy and what are the likely effects?
B) Why do profit-maximizing firms attempt to set marginal revenue equal to marginal cost?
C) How are the terms of trade determined when countries choose to engage in international trade?
D) What are the goals and tools of macroeconomic policy?