Drugs or chemicals can: a. all of these choices are correct. b. facilitate the transmission of information from one neuron to another. c. inhibit the transmission of information from neuron to another. d. be used to cure a whole variety of clinical disorders by playing a role at the synaptic level.

A. All of these choices are correct.

Explanation:

In pharmacology , drugs play different roles from simple to complex.

as is the above mentioned question drugs can facilitate the transmission of information from one neuron to another so option B is correct.

While the drugs / chemicals can  inhibit the transmission of information from neuron to another so option C is also correct.

And the drugs can also be used to cure a whole variety of clinical disorders by playing a role at the synaptic level.

Hence option A All of these choices are correct is the right answer.