Final answer:
The correct term for a nuclear family created through marriage and childbirth is 'family of procreation'. It contrasts with the 'family of orientation', which refers to the family one is born into.
Step-by-step explanation:
The term for the nuclear family that is formed when one marries and has children is A. family of procreation. This is distinguished from the family of orientation, which is the family unit into which a person is born and raised. As sociologists would describe, a family of procreation is a socially recognized group that individuals enter into typically through marriage, encompassing the intimate relationships and economic bonds formed between spouses and their children. This concept relates closely to societal and cultural significance, especially with matters regarding lineage and the continuation of family traditions and identities.