Which Unifying Theme in Psychology Is Best Reflected by the Observation

Which unifying theme in psychology is best reflected by the observation that the development of psychological disorders involves an interplay among a variety of psychological,biological,and social factors

A)  People's experience of the world is highly subjective. 
B)  Behaviour is determined by multiple causes. 
C)  Psychology is empirical. 
D)  Psychology evolves in a sociohistorical context.