How are visual aids used most effectively in a speech?
a. to support a speaker's point by providing evidence or clarity
b. to provide additional information that the speaker doesn't mention
c. to cite the sources of the information that the speaker is using
d. to establish credibility for the speaker by using quotations

The additional information that the visual material can provide comes to support the speach for a better understanding ( to reach the audience more effectively depending on the structure of the audience cause man- for example- have the tendency to remember better what they see rather then what they hear

boccaccio employs the voice of his narrator dioneo to represent his ideas on the tension between masculinity and femininity.  while dioneo excites the members of the brigata and recognizes women for their unique skills and independent ideas, he concludes the decameron with a story reminiscent of the society from which these young aristocrats escaped, revealing misogynistic overtones.  dioneo boccaccio is able to explore the gender disparity which is inherent in 14th century florentine society.

hasty generalization