Answer:
Self- perception theory
Step-by-step explanation:
Self-perception theory: The theory is proposed by Daryl Bem.
According to him, an individual develops an opinion and attitude or behavior by observing and interpreting his or her own behavior and then draws a conclusion from it. He believed that a person's emotions and internal thoughts lead to attitude formation.
The conclusion made by Marcia about Jan in the above question is based on the process of self-perception theory.