DSST Principles of Public Speaking (CLEP) Practice Test 2025 – Your All-in-One Guide to Exam Success!

The correct answer is supporting materials, as narratives, expert testimonies, blood tests, and statistics all serve to enhance and substantiate the content of a speech or presentation. Supporting materials provide evidence and context that help to clarify, demonstrate, or reinforce the speaker's main points. They can take various forms, such as anecdotes that engage the audience emotionally, expert testimonies that lend credibility, statistical data that provide quantitative backing, and even tangible evidence like blood tests that can support scientific claims.

Incorporating supporting materials into a speech not only helps to persuade the audience by offering concrete proof, but it also enhances the overall effectiveness and reliability of the argument being made. It aids in establishing a stronger connection between the speaker's claims and the audience's understanding, making the speaker's case more compelling and trustworthy.