Treatment with a Drug That Inhibits MAO May Slow Down

Treatment with a drug that inhibits MAO may slow down the progression of Parkinson's disease because

A) MAO may metabolize environmental chemicals into toxins that damage dopamine neurons.
B) MAO reduces the availability of dopamine in brain neurons.
C) MAO metabolizes serotonin, which in turn inhibits dopamine activity.
D) Parkinson's results from consumption of MPTP.
E) B and C are correct.