Explanation:

Here’s the thing—let’s break it down:

- In polyandrous families (? Option 1), one woman has multiple husbands at the same time. Because of this, it’s not always obvious who the biological father of a child is. That’s why they often have to separate the idea of “biological father” (the one the child is genetically related to) from “social father” (the man who acts as the dad in practice).

- Patriarchal families (Option 2) are run by men—the oldest or the father. Here, the role of “father,” both social and biological, is usually held by the same guy.

- Matriarchal families (Option 3), on the flip side, have women at the core and in charge, but there’s no built-in confusion between biological and social fatherhood.

- Joint families (Option 4) involve extended family living together—grandparents, uncles, aunts, cousins. Still, the biological vs. social father difference isn’t a core issue here.

So yes, Polyandrous family is where that distinction really matters. Good catch.