I’d be very grateful for some help with understanding the following chess puzzle. The following starting position for white is given: 
The solution sees the queen taking the rook. But instead of the second black rook taking the queen, the black queen is supposed to take the pawn?
Solution:

Cam someone explain why that would be the best moves?
After … Rxe2 there is a forcing sequence by white: Re8+ Kf2, Nd6+ forking the king and queen. If black takes on c2 with check first, the white queen can be captured by the rook without the follow-up forcing sequence. So black wins back one pawn, in comparison.
Because if Rxe7 then Rd8+ wins, either by
Re8 Rxe8+ Kf7 Nd6#
or
Kf7 Nd6+ Kg6 Nxc4
Qxc2 is kind of a desperation move - since after Rxe7 the queen is already lost by force as above, sacking the queen on c2 at least forces the king out, and after Rc8+ the back rank is defended. Black is still dead lost but at least the immediate mate is prevented by sacking the queen to weaken the king and secure the 8th rank. The knight is also pinned temporarily so it relieves a lot of the immediate pressure in the position, but stockfish still rates it as +5.9 after Rc8

