The correct option is B.
Visual aids refer to pictures, charts, graphs and all other visual tools that are used to supplement words when delivering speech. Visual aids are very useful in public speech for a number of reasons;
1. They help the audience to understand the information that the speaker is passing across and also help them to remember the details of the speech.
2. They increase the audience's interest by capturing their attention.
3. They act as reminder for the speaker.
4. Visual aids make one's speech more persuasive compare to one that does not use visual aids.
Thus, generally, visual aids are of great importance in clarifying complex matters for one's audience.