Final answer:
The structural-functionalist perspective views marriage as a social institution that legitimizes having children and contributes to social stability.
Step-by-step explanation:
The theoretical perspective that highlights society's need or demand for marriage to legitimize having children is A. structural-functionalist. This perspective views society as a complex system whose parts work together to promote solidarity and stability. Within this framework, marriage is seen as a social institution that serves several essential functions, including the legitimization of children. Marriage contributes to social order by establishing clear norms for behavior, thereby reinforcing the family structure and providing a stable environment for the upbringing of children.