Final answer:
The study of common sense knowledge used to understand social situations is known as Social cognition, a domain closely related to cognitive psychology and intersecting with social epistemology within the broader field of epistemology.
Step-by-step explanation:
The study of common sense knowledge that people use to understand situations they're in is known as Social cognition (option A). This branch of psychology focuses on how individuals consider social clues to understand and interpret situations in the social world. Cognitive psychology is related to this field in that it focuses on the study of human thinking. Social epistemology is a subset of the broader field of epistemology, which studies knowledge and its acquisition, but with a focus on social processes and how knowledge is justified within groups.