Which of the following is an example of using a person as a presentation aid?

a.

referring to an expert during a discussion of health care

b.

demonstrating the latest haircut techniques using a friend as a model

c.

asking a member of the audience a question

d.

acknowledging feedback from the audience

The correct answer should be B. demonstrating the latest haircut techniques using a friend as a model

The other possible answers shouldn't be it because they only refer verbally to someone or are not used in presenting something. In b, you use your friend as if he were a presentation or something similar.