Recent Research and Increased Understanding About the Role of Neurotransmitters

Recent research and increased understanding about the role of neurotransmitters in psychopathology point out that

A) each psychological disorder is caused by a deficit in a specific neurotransmitter.
B) chemical imbalances of the brain are the cause of psychopathology.
C) simple cause/effect conclusions stating that an individual neurotransmitter abnormality causes a disorder are incomplete.
D) neurotransmitters have very little to do with psychopathology for most individuals but may be the single cause of disorders for others.