Answer:
D. Mr. Winter asks her to babysit even though she has never seen him before; this unusual approach is a clue that something is off concerning the Winter family.
Explanation:
In this story, Harriet is babysitting Charles, who is the baby of the Winter family. However, she is confused about the reason why they asked her to babysit. She met Mr. Winter at the swim club, and he immediately requested this, even though he knew nothing about her. Moreover, when she is at the house, she is asked to not look in on the baby at all. All of these details indicate that there is something strange going on in this family.