The study of unemployment is the subject matter of which one of the following Economics?

Correct option is D

Macroeconomics is the branch of economics that focuses on the overall behavior and performance of the economy as a whole. It examines broad economic phenomena, including aggregate variables such as national income, employment, inflation, and economic growth.
Unemployment is a macroeconomic concept that refers to the number of people who are actively seeking employment but are unable to find jobs. Macroeconomists study unemployment to understand its causes, consequences, and implications for the overall functioning of the economy.