Economic science is concerned with studying economic phenomena at the broadest level, by macroeconomics, and at a strict level, by microeconomics.
Macroeconomics studies the economic policies of governments and the large aggregate indicators of the economy, such as inflation, unemployment and the rate of juts.
Microeconomics focuses on the environment in a restricted environment, analyzing the behavior of the consumer, the behavior of the firms and the relationship between them. For this, there are specific theories: Firm theory and Consumer Theory.
The answer, then, is microeconomics.
