The technical answer would be "an extended family," but seeing as though your answers are limited, it would have to be D.
Think about it this way:
A: A foster family is when another, separate, family takes care of a child/children from another. When you foster a cat, you take the cat in and care for it.
B: A blended family is a couple(the mum and the dad) with their children from their current and previous relationships.
C: The typical, everyday family. A mum, a dad, and their beloved children.
D: Multigenerational. When you think, "generations in the family" is the line of parent to parent. There is the grandfather(one generation), the father(Thw grandfather's son, the second generation), and the son's children(the dad's children, the third generation).
I'm sorry if this is confusing in any way, but I hope it helps. ^-^
