18. Nowadays, you can learn more about a product or service through ______. 
A. a news report
B. an infomercial
C. a webinar
D. a documentary
19. This is used when movement and action are important parts of the presentation.
A. video
B. vlog
C. webinar
D. multimedia messages
20. Viewing materials increase ____________.
A. audience engagement
B. the speaker’s personal appearance
C. audience impatience
D. the speaker’s artistic ability​