another puzzle

i am not sure if this was the best option but if i was wrong tell me in the comments

c5 is not the best move for black, but assuming they do play c5, there is actually a mate in 3 available for white!
1. Ra8 is absolutely correct, checking on the back rank and forcing black to block with their bishop.
2. Qd6 is best here, as the black bishop is pinned by the white rook, and creates a sort of cage that black can't escape.
3. Rxb8 is checkmate no matter what move black plays.
Bonus: If they play b5 or b6, you can mate with the queen (Qxb8).
Remember, you can use the magnifying glass icon at the bottom left of the puzzle to analyze the best moves.
Hope this helps!