【单选题】What is the fundamental difference between microeconomics and macroeconomics?
A.
Macroeconomics involves studying the economy as a whole, while microeconomics involves studying the behavior of individual industries, firms, and households.
B.
Macroeconomics concentrates on those parts of the economy involving very large amounts of money, while microeconomics concentrates on those parts of the economy involving small sums of money.
C.
Macroeconomics studies the behavior of large firms, while microeconomics studies the behavior of small firms.
D.
There is no difference, basically macroeconomics and microeconomics are one and the same.