What two devices in a computer are black boxes

Which of the statements below describe the guidelines for the use of text in presentation programs? a. do not use numbered lists. b. fonts should be appropriate for your audience. c. limit the number of fonts you use to three or four. d. only use bulleted lists for sales promotions. e. select font sizes that are appropriate for your delivery method. f. use font colors that work well with your background. select all that apply