Which Statement About Agonist and Antagonist Drugs Is True

Which statement about agonist and antagonist drugs is true?

A) The target tissues for these types of drugs are invading bacteria and viruses.
B) Both agonist and antagonist drugs must interact with receptors to produce their intended responses.
C) Antagonist drugs produce only intended responses and agonist drugs produce both intended responses and side effects.
D) These types of drugs are less likely to cause allergic responses than drugs that are neither agonists nor antagonists.