Answer and Explanation:
Economy is divided into two main fields: Microeconomics and Macroeconomics. Microeconomics studies the decisions of individuals and businesses while Macroeconomics is in charge of analyzing the economy as a whole including decisions made by governments and their countries. Thus:
A) The effect of government regulation on a monopolist's production decisions (Macroeconomics).
B) The optimal interest rate for the Federal Reserve to target (Macroeconomics).
C) The government's decision on how much to spend on public projects (Macroeconomics).
