Which Best Describes the Specific Cause of Parkinson's Disease

Which best describes the specific cause of Parkinson's disease?

A) Enhanced sensitivity of cholinergic receptors to acetylcholine
B) Reduced ability of neurons in the substantia nigra to release dopamine
C) Failure of serotonin receptors to bind with these neurohormones
D) Hyperactivity of metabolic enzymes that degrade dopamine
E) Natural tendency of basal nuclei to follow a daily recurring,oscillating cycle of rising and falling norepinephrine release