Why didn't Kasparov take the rook on d5?
1.If he had taken with the knight then QXg7#2.If he had taken with the queen then Ne7 and there is a fork for queen or king!!That's why he didn't take the rook.
Taking with the queen at least nets a rook and knight for the queen and b5 pawn, and forestalls the loss of the c4 pawn. Still a losing position!