The branch of psychology that studies how a person's thoughts, feelings, and behavior are influenced by the presence of other people and by the social and physical environment is called:

Social Psychology

Explanation:

Psychology is the empirical study of how people think, feel and behave. Social psychology refers to the impact of the presence of other people on how one behave, feel and think. In other words, it is the study of human behavior in the context of society. It determines the factors which led us to behave in a certain way while interacting with others.

"choosing is refusing" means individuals face an opportunity cost with each decision they make. economists state that every decision involves trade-offs. opportunity cost is the least desirable alternative given up as a result of a decision.