An instructor can respond to students' questions that may be complex, illogical, or off topic by:

Deferring questions that are beyond the scope of the lesson is an effective strategy for instructors because it maintains the focus and flow of the class. When a question veers off-topic or becomes overly complex, it can distract from the core material being covered, potentially leading to confusion among students. By deferring such questions, the instructor acknowledges the student's inquiry but also sets a boundary to ensure that the essential learning objectives are met during the session.

This approach allows the instructor to address the student's question later or in a different context, perhaps suggesting a follow-up discussion or a resource where the student can find more information. It reinforces the importance of staying on track with the curriculum while still validating the student's curiosity and engagement.

Addressing other options: Providing an immediate answer may seem efficient but can disrupt the learning environment and lead to misunderstanding. Bluffing by giving false or misleading information not only undermines the instructor's credibility but can also severely hinder students' learning. Engaging in brainstorming with the class could be productive but may stray further away from the lesson's goals and timelines, which is not ideal in a structured learning environment.