A predicate is the part of the sentence that tells what the subject is all about. A predicate can either be simple or complete. A simple predicate is the main verb used in the sentence; whereas, a complete predicate includes the main verb and its complements. In the given sentence above, the simple predicate is the verb "teach".
You didn't include the answer choices, but a question with the same wording popped up on the quiz I just took and the answer for me was B : They suspect something strange may be going on.
