Final answer:
The correct answer is option a. Among the options, 'become absent-minded' is the best match for the word 'wander' because it can refer to someone's thoughts drifting without focus, similar to physically wandering without a destination.
Step-by-step explanation:
The word "wander" generally means to move or travel with no fixed purpose or direction, or to drift physically or mentally to different thoughts, purposes, or tasks. Among the options provided, a) become absent-minded best matches the word "wander".
This is because when someone is described as wandering, it can also mean their thoughts are drifting and they are not fully focusing on the task or conversation at hand, which is similar to becoming absent-minded. Therefore, "wander" doesn't match with b) profit, c) plenteousness, or d) moron.