The spouse of a patient diagnosed with schizophrenia says, "I don't understand why childhood experiences have anything to do with this disabling illness." Select the nurse's response that will best help the spouse understand this condition.

A) "Psychological stress is actually at the root of most mental disorders."
B) "We now know that all mental illnesses are the result of genetic factors."
C) "It must be frustrating for you that your spouse is sick so much of the time."
D) "Although this disorder more likely has a biological rather than psychological origin, the support and involvement of caregivers is very important."