Microeconomics: Micro means small. It is the brach of economics
which involves the study of decisions made by household and
businesses about allocation of resources and prices of goods and
services. The main objective of microeconomics is to examine how a
firm or an individual can maximise its production or consumption
capacities with the given amount of resources.
Macroeconomics: Macro means large. It is the brach of economics
which deals with the relationship between various factors in the
economy. The main objective of macroeconomics is to regulate the
economy’s growth and stability using macroeconomic tools such as
interest rates, money supply, taxes and government spending.
In the given options, option (a) is a microeconomics topic as it
involves the decision-making of an individual firm. Option (c) and
(e) are macroeconomic topics as they are related to overall economy
on a whole.
Thus, the answer is (a).