During a dental procedure, Xavier is injected with a drug that is designed to greatly reduce his pain by interfering with the sending of pain signals. At the neural level, the drug is preventing

a. action potentials from being transmitted.

b. neurotransmitters from being reabsorbed by neurons.

c. potassium ions from being released at the terminal buttons.

d. pain signals from being clearly interpreted in the sensory cortex.

e. the myelin sheath from protecting the axon.