Rachel's mic is always off until I turn it on. So if she's asking a question, it's only after she's visually indicated that she wishes to do so, and I've found a time in my presentation that I'm ready to take it. So I'm literally never being interrupted, and can't be surprised by the fact that she's asking a question (although I may well be surprised by the content).

I do try to limit the time I wait to take a question, since I don't want to move on with a topic where I've failed to properly explain some foundational piece.