Question

lend expert support to your arguments and provide additional witnesses to give credibility to your speech.
a. examples
b. narrations
c. testimonies
d. statistics

Explanation:

Testimonies are statements from individuals, often experts or those with relevant experience, which provide expert - level support and add credibility to a speech by acting as additional witnesses. Examples, narrations, and statistics serve other purposes in a speech.

Answer:

C. Testimonies