Neurotransmitters Can Have an Excitatory Effect or an Inhibitory Effect

Neurotransmitters can have an excitatory effect or an inhibitory effect at the postsynaptic membrane. The difference between these two effects is that

A) an excitatory effect makes the postsynaptic cell less negative, and an inhibitory effect makes it more negative.
B) an excitatory effect decreases the likelihood of an action potential, and an inhibitory effect increases the likelihood of an action potential.
C) an excitatory effect is caused by the neurotransmitter binding to the receptor whereas the inhibitory effect is caused when the neurotransmitter is denied access.
D) an excitatory effect stores the neurotransmitter, and an inhibitory effect releases the neurotransmitter.
E) an excitatory effect hyperpolarizes the postsynaptic cell, and an inhibitory effect polarizes it.