L-DOPA Is Combined with Carbidopa Because

L-DOPA is combined with carbidopa because:??

A) Carbidopa potentiates the action of L-DOPA
B) L-DOPA cannot cross the blood-brain barrier
C) Carbidopa prevents peripheral conversion of L-DOPA to dopamine
D) Carbidopa has additional anti-Parkinson effects
E) Carbidopa prolongs the half-life of L-DOPA