Diagram's position shows a bit of 2nd game Anand-Topalov: what's the correct, logical move for black, and why?

We'll see...
After a catalan opening, Vishy proposed the change of queens, even doubling pawns on a-column. This is really "the problem" for white?

Not, because
any pawn structure is compensated with enough activity of the rest of pieces, such as Anand really demonstrated in the game.

So, if activity - for the creation of weak points in black's position - is all that white needs firstly, black needs:
- To change any active pieces of white.
- Activate their own pieces.
First question (what pieces...?) is answered thinking that Nd3 was there near all the game, not getting play to black bishop (Bb8).

His mission, joined with f4 pawn, was not only control e5 square, really was that black don't move e5-e4:
- a) getting out Nd3,
- b) closing Bg2 diagonal
- c) to give play to Re8 and future Bb8.
So, which move is probably best for black?
One move which:
- give play to Re8 and Bb8
- change white Nd3, even giving a future d4-d3 possibility
- stay a knight on e3, or generate counterplay about it.
Is "easy" to think something like this at home, or analysing the game in the club, sure :-)
Ok, here is a possible solution

- what I have seen (in part) in any publications or GM's comments:
If the game was developed with something like that... who knows!
