Final answer:
External circumstances influence the expression of a personality trait according to trait-situation interaction, which is a blend of personality and situational influences on behavior. The answer is option C.
Step-by-step explanation:
External circumstances influence the expression of a personality trait according to c. trait-situation interaction. This concept is studied within social psychology, reflecting the complex interplay between internal factors such as personality traits, and external factors including situational context.
Behavioral genetics determinants theory explores how both genetic and environmental variables contribute to behaviors and traits, while behavioral factor analysis might be concerned with observable behaviors and their correlation with environmental stimuli. Psychoanalytical theory, notably different from the others, emphasizes the influence of unconscious processes and early childhood experiences on personality development.