An essential difference between somatic system disorders and dissociative disorders is:

An essential difference between somatic system disorders and dissociative disorders is:
 
  a. Somatic system disorders are under voluntary control, whereas dissociative disorders are unconscious and automatic.
  b. Dissociative disorders are precipitated by psychologic factors, whereas somatic system disorders are related to stress.
  c. Dissociative disorders are individually determined and related to childhood sexual abuse, whereas somatic system disorders are culture bound.
  d. Dissociative disorders entail stress-related disruptions of memory, consciousness, or identity, whereas somatic system disorders involve the expression of psychologic stress through somatic symptoms.