Which of the Following Best Defines a Family

Which of the following best defines a family?

A) Two parents living with their biological children
B) Roomates in a dorm or apartment who plan to stay together throughout their college years
C) A group of neighbors on the same block who have lived on that block for over a decade and who are very fond of each other
D) Two or more people related by birth, marriage, adoption, or choice with emotional ties and responsibilities to each other