What characteristic distinguishes a nuclear family from other family structures?

A nuclear family is specifically defined by its composition, which includes two parents and their biological or adopted children living together as a single unit. This structure emphasizes the primary parental relationship, marking a clear distinction from other family structures such as extended families, which may include additional relatives like grandparents, aunts, uncles, and cousins. This composition is central to the definition of a nuclear family and highlights the focus on the immediate family unit.

The other options fail to define a nuclear family correctly. For example, equal distribution of property can occur in various family types and does not pertain specifically to the nuclear family structure. Inclusion of extended family members is characteristic of extended families, not nuclear ones. Lastly, responsibility sharing among relatives is a feature commonly seen in broader family networks, rather than being a defining trait of a nuclear family. Understanding these distinctions is essential for recognizing different familial structures and their characteristics.