Final answer:
the correct answer is: a. her children moved away.
Step-by-step explanation:
Empty-nest syndrome refers to the feelings of sadness and loss that parents may experience when their children leave home, typically to start their own lives as adults. In this case, since Angela is experiencing empty-nest syndrome, the most likely scenario is that her children moved away recently.
Based on the given information, Angela is feeling alone and the house seems empty without her family. This aligns with the emotions associated with empty-nest syndrome where parents may feel a sense of loss, emptiness, and a lack of purpose when their children no longer live at home.