Correct answer is:
By showing evidence that represents what the speaker is talking about.
Explaination
VIsual aids are an amazing tool for speakers. They fulfill many functions during a speech, like making a more memorable impression of the topic, engage the audience and of course, they can act as clarifiers and reinforcements of the point the speaker is trying to make. Visual aids can come in many forms like video, pictures, charts or even props. And I must mention that nowadays with the advance of technology and how many things are trying to steal our attention away, I consider a visual aid a must