Answer:
The correct answer is a. personality
Step-by-step explanation:
A personality of an individual define the individual's way of thinking, his behaviors towards others, his emotions and feeling. Personality psychology is the science in which psychologist studies the similarities and differences in these characteristics between different people and groups.
So here individual differences especially variation in an individual’s characteristic way of thinking, feeling, and behaving is being recognized so it is referred to as personality. There are two broad areas in personality studies one that focus difference in personality characteristics and other focuses on how various characteristics comes together as a whole.