The correct answer is “
A. His monologue allows him to share his ideas to the crowd without interruption.”
This speech where Marc Antony is speaking to the crowd is an important one because of the information being presented, both, to the crowd and readers/audience members. Because of its importance, a good way to ensure the most is taken from the speech is to not have the speaker interrupted in order for the message to make the most impact. Thus, this is most likely what motivated Shakespeare to have this information conveyed as a speech/monologue. (Note: We know it is not a soliloquy because a soliloquy is where a character speaks only to himself or herself.)