Use reasoning to lead to the answer of the following question:
Which of these sentences doesn't make sense?\nOptions:\n- Sentence A: "Obama delivered a speech with a microphone in public"\n- Sentence B: "Obama delivered a speech with a microscope in public"\n

Sentence B
Microscopes are used for enhancing vision, one would not serve a purpose during a speech.

.

So, the final answer is Sentence B