Answer:
C. Please keep track of the number of times you say YOU KNOW when you speak.
Step-by-step explanation:
In English, italics are often used for emphasis or to indicate that a word or phrase is being used in a special or unusual way. In this case, the phrase "you know" is being singled out as an example of a phrase that the speaker may be using frequently, so it's appropriate to italicize it.
Option A and B do not use italics correctly. In option A, there's no need to italicize the word "movies". In option B, there's no need to italicize the word "about". These words are not being used in a special or unusual way, nor are they being emphasized in the context of their sentences.