William is prescribed a drug from his doctor, and then prescribed a different drug from his dentist. he did not tell either doctor about the other prescription. unfortunately, when taken together, drug one cancels out drug two, so the secondary drug has no effect. this type of drug effect is:

This kind of effect between the two drugs is called antagonism.

Explanation:

By definition, antagonism means opposition, hostility, antipathy; contrary position or situation; rivalry, fight. In the case of medications, their response may be suppressed or reduced in the presence of another, often by the competition between them. These interactions may generate beneficial responses or not. An example of antagonism can be seen in the question above, where William took two drugs that he did not know were antagonists, the result of which was that drug number 1 inhibited the action of drug number 2.

the answer is "a.) well–developed vascular system."

explanation: