Answer:
The rule he is using is to use a few lines of text.
Explanation:
Terrance is preparing to use visual aids in his presentation. This is a great idea, since the visuals are able to draw the audience's attention efficiently, in addition to allowing some information, from the presentation, to be highlighted.
However, to use visual aids in presentations it requires that some rules be followed. One of these rules is to use a few lines of text, which is what Terrance is doing. By using a few lines of text, Terrance is able to draw the audience's attention to a specific theme, but without taking his attention away from what he will say about that theme. In addition, when using this rule, Terrance provides a clean presentation without excess information that will tire listeners.