When Lewis Smokes, the Nicotine from the Cigarettes Will Affect

When Lewis smokes, the nicotine from the cigarettes will affect his brain cells by

A) causing more neurotransmitters to be released.
B) prolonging the action of certain neurotransmitters.
C) directly stimulating brain cells by mimicking specific neurotransmitters in the brain.
D) filling receptor sites on brain cells and blocking incoming messages.