This is a little bit of a mess. In d4 + e3 structures with the dark square bishop inside the pawn chain, c4 is usually played for. A4 is certainly a common move in many d4 lines, often to restrain b5, but I'm not sure what it is doing here, and most especially what b3 has to do with anything.
I think your effort to study this pawn structure without presenting a game you played is misguided. With a game for context, we could help a lot more.
I'd like to know about pawn structure in the diagram. The position is theoretical / unlikely / for illustration purposes only.
Here is version 1.
Here is version 2.