Which Statement Best Describes Mood Disorders and Schizophrenic Disorders,according to the Stress-Vulnerability

Which statement best describes mood disorders and schizophrenic disorders,according to the stress-vulnerability model

A)  Vulnerability to these disorders is determined by heredity alone. 
B)  Vulnerability to these disorders is determined by the environment alone. 
C)  Traumatic stress is the major cause of these disorders. 
D)  These disorders emerge when high biological vulnerability combines with high stress.