Although Fewer Parents Are Married Now Than in the Past,why

Although fewer parents are married now than in the past,why are many children involved with more than two parents?

A) People are more likely to have "parents of choice" in addition to biological parents.
B) A growing number of families include stepparents and siblings from parents' previous relationships.
C) The suburbanization of America has meant that children spend more time at other people's houses.
D) Younger people are reaching out to older people more with the aging of the Baby Boomer generation.