A certain drug prevents a neurotransmitter from initiating a response in the receiving neuron. Which of the following statements best describes the mechanism by which the drug may be acting?
a) The drug is preventing the neurotransmitter from binding to its receptors in the receiving neuron.
b) The drug is causing more neurotransmitter molecules to be released.
c) The drug is preventing the neurotransmitter from being degraded.
d) All of the listed responses describe how the drug may be acting.

The correct answer is statement a.

Explanation:

Endogenous chemicals that take part in neurotransmission are known as neurotransmitters. It is a chemical messenger that performs transmission of impulses across a chemical synapse, that is, from one nerve cell to another. The neurotransmitters get discharged from the synaptic vesicles and pass onto the synaptic cleft, where they get attached to the receptors present on the target cells.  

However, there are some of the drugs, which prevents the binding of a neurotransmitter with its receptor known as receptor antagonists. These antagonists or drugs prevent a neurotransmitter from starting a response in the receiving nerve cell. Some of the receptor antagonists are beta-blockers, alpha-blockers, and calcium channel blockers.