Answer:
B. systematic study of society and social interaction
Explanation:
The purpose of sociology is to understand the basic patters of human interactions and understand the reason of people's behavior in that interactions.
In order to find this out, sociologists need to conduct a systematic study. Meaning that they need to observe those social interactions and analyze them with scientific method. To make sure that they arrive at a right conclusion, They have to consider several factors that might influence the behaviors such as Culture, psychology, societal norms, and many others.
