An hourglass sequence begins with open questions, proceeds to closed questions, and concludes with open questions.

Isaac is giving a speech on influenza vaccinations. During the speech, he says, "Research by Yuri Titov, M.P.H., has shown that in a typical year the vaccine is 70 percent effective at preventing infections, that approximately 60 percent of Americans get vaccinated, and thus there are about 40 percent fewer cases of the flu each year than there would be without the vaccine." Isaac has

A. established the source's credibility through the use of statistics. B. not established his source's credibility. C. established the source's credibility by mentioning the author's educational qualifications. D. established the source's credibility by showing the source is affiliated with a trusted organization.

If your presentation aids overpower your speech instead of embellish it, you probably did not follow which guideline for effective aids?

A. Have a backup plan. B. Practice with your presentation aids. C. Remember your goal. D. Consider the context.