Correct Answer: Microeconomics

Solution : The concept of demand and supply is a key topic in (b) Microeconomics.

Microeconomics focuses on the behavior of individual economic units, such as consumers and firms, and their interactions within specific markets. The study of demand and supply is fundamental to microeconomics. It examines how consumers' preferences and willingness to pay determine the demand for goods and services, and how firms' production decisions and cost structures influence the supply of goods and services. Microeconomics analyzes the interplay between demand and supply to determine market equilibrium, prices, and quantities exchanged in individual markets.