Concept:An antonym is a word with the opposite meaning. "Assert" means to state confidently. Its opposite is to refuse or reject.Explanation:"Assert" means to say something firmly and forcefully. For example, she asserted her innocence."Deny" means to refuse to admit or accept something. It is the direct opposite of assert.Options like maintain, proclaim, and declare are similar in meaning to assert, not opposite.Hence, the antonym of "assert" is "deny".Answer:Option A: Deny