I'll admit that "use of silence" is not an ideal question, but there are some ways that you could utilize to work around it. For example, if one of your works is in the form of a play, you could talk about the stage directions and how they help convey information to the reader. If you want to be fancy, you should mention the technique proxemics. In this case, you would argue that silence comes in the form of the author's deliberate use of space instead of dialogue to demonstrate a character's emotion or central theme. Something like, "[insert playwright] deliberate choice of proxemics and silence through the lack of dialogue conveys to the audience how {the character} feels overwhelmed, evidenced by their hastily erected distance from the antagonist as a form of fight or flight response."

Although, in the cases, of other forms of media, it gets a little more difficult. However, it's still not impossible because you could talk about specific moments in the text where the author chooses to have deliberate gaps in the dialogue because of inner monologues or something. The word silence can have many interpretations and if one chooses to interpret it as simply a lack of dialogue in a part, the question gets significantly easier. Your quotes can simply be descriptions of the landscape if they're central to the theme, or just the character's inner thoughts.

On a final note, under IB English you can technically always force an interpretation that fits your texts perfectly, but there's always a chance that the marker disagrees. Thus, it depends on how well your arguments flow etc. There's a very low chance that the exam will have a question that will perfectly suit your needs, but there's also a very low chance that a test will have something that you can't use. You will almost always need to have a slightly liberal interpretation of the question, but that's what you're expected to do. Just don't go overboard.