Answer:
a. The effect of government regulation on a monopolist's production decisions: microeconomics
b. The government's decision on how much to spend on public projects: macroeconomics
c. The effects of the Internet on the pricing of used cars: microeconomics.
Step-by-step explanation:
Le re-visit the concept of microeconomics and macroeconomics before we apply them to solve the problem.
Microeconomics studies about the behavior of players and how players in the economy ( individuals, households, firms) making decision of resources allocation, how they interact with one another. Thus, it usually studies about market of goods and services.
Macroeconomics studies about economy as a whole, that is, its structures, performances, behavior ( e.g: inflation, unemployment, GDP growth)
a. is microeconomics because it is about how monopoly firms decide its production level given changes in government's regulations.
b. is macroeconomics because it is about public spending ( spending for the whole economy)
c. is microeconomics because it is about how market of used cars is affected ( in term of pricing) as sellers and buyers have new ways of delivering/finding information and connections.