Did Bob _____ that he locked the door?

• A. Realize
• B. Forget
• C. Mention
• D. Assume

Answer: (A)

This sentence tests choosing a verb that expresses awareness of a fact introduced by a that-clause. Did Bob realize that he locked the door? fits because realize means to become aware of something as a fact. The base form after did is correct, and the that-clause states what he could have become aware of.

Other options shift the meaning: forget would imply he didn’t remember the fact; mention would imply he told someone about it; assume would suggest he believed it without proof. None of these capture the idea of him recognizing or understanding the fact that he had locked the door, so realize is the natural and best choice.