Final answer:
The simple subject in the provided sentence is 'clock'. It is the main noun that the sentence is about, focusing on the care to be taken with it.
Step-by-step explanation:
The simple subject in the sentence "During the house move, be particularly careful with this antique clock" is d) clock. A simple subject is the main noun or pronoun that tells us what or whom the sentence is about. In this sentence, despite the direction to be careful during the house move, 'clock' is the focus of the sentence, making it the simple subject.