What is the defining characteristic of a 'single-parent family'?

A single-parent family is defined as a family unit in which one adult is solely responsible for raising and caring for one or more children. The defining characteristic is that only one parent is present in the household, whether due to divorce, separation, death of a spouse, or the choice to raise children independently. The single parent takes on the roles of both caregiver and provider.

The other options misinterpret the term:

• Living in a single house describes a household arrangement, not a family structure. Many different family types live in a single house.
• Having a single child describes the number of children (a one-child family), not the number of parents. A single-parent family can have multiple children.
• Having a single income may sometimes be true of single-parent families, but it is not the defining characteristic. Some two-parent families also have a single income, and some single parents may have multiple income sources.

The word "single" in "single-parent family" refers specifically to the number of parents, not to the house, income, or number of children.