Argumentative is an evidentiary objection raised in response to a question which prompts a witness to draw inferences from facts of the case.
For example, if a lawyer on direct examination were to ask his witness, "So he was driving negligently?," opposing counsel could raise an argumentative objection. This is because negligence is a legal term of art, and the witness cannot reasonably answer the question. Since the lawyer is "arguing" his case through the witness, the objection would be sustained, and then stricken from the record.
So what is the adjective for questions that do not ask to draw inferences or, I guess additionally, to state opinions? I think not 'objective' otherwise we might say 'subjective' instead of 'argumentative'. Same for 'direct': 'indirect'