Young adults, who return after leaving home for some period of time to live in the homes of their middle-aged parents, are termed
a. yo-yo children
b. sandwich children
c. boomerang children
d. empty nest children

The correct answer is C. Boomerang children

Explanation:

The term "Boomerang children" is used to refer to young adults that left their parents' house in the past but return to leave with them, usually due to economic or financial reasons. For example, young adults might return to their parents' house after college to save money. Additionally, the term "boomerang" is used because similar to a boomerang children return to the started point; moreover, this term is mainly used to describe the last generations in western cultures as nowadays it is tendency people go back to their parents' house after college or university. Thus, that term that describes young adults who return after leaving home is boomerang children.