Answer:
providing a resource for the answer
Step-by-step explanation:
If she guessed the answer to the question it could be be incorrect and the student would believe that's the correct answer even though it's wrong. So, this isn't the answer.
If she states that the question is not relevant, that can be perceived as rude since the student probably asked a question relevant to the presentation she gave. So that's not the answer either.
Asking if the student has any other questions is ok, but she has to admit that she doesn't know the answer to the question the student just asked. So probably not an answer.
But, providing a resource that has the answer is much more cordial and respectful to the student. Now the student can get the answer to the question they asked. So this is the most appropriate way for Sarah to respond.