The way I see it is that symbolic interactionism is looking at how INDIVIDUALS are interacting in a society and how they are affected, and therefore you can eliminate B and C automatically. A sounds better than D and I didn't even read the passage. I'm pretty sure B is representing conflict theory because it is talking about power differentials among the groups. Just remember that symbolic interactionism is microsociology and the others are macro.
I personally don't see how B represents functionalism, I would have to read the explanation. It clearly seems like B is conflict theory unless my sociology is off. C and D is talking about segregation so maybe they are referring to conflict theory in that context, but the clear answer is A if you know these terms