why not Rc1 and threating Rc8 mate??

Because the bishop can go to g8 and Rh8 is stalemate and if Rh6 then bishop h7 and after it is taken it is stalemate.

Interesting and good practice, thanx for sharing...

because if u move Rc1 then black will play Bc2, if u take that bishop it will be a stalemate.. if u dont take that bishop u still have a winning move but u have to make more moves for winning..

Because black can respond with Bf5 and cannot be taken due to stalemate,  you still have a win, but it will take a little longer.

... but the one given is the only one that does the job in two moves.

White has to be careful here, because they cannot touch the black bishop, as it is the only black piece that can move (unless one of the knights is moved of course). So black can use the bishop to block (almost) any approach to the 8th rank by the rook. So Rg2, Bg6, and black cannot take the bishop, and has to find another route (Rb2, any bishop move, Rb8#). Rc1, Bc2 and again white needs an extra option (Kd4, any bishop move, Rc8#). Anyway, here are some lines...

good

Very very easy

Rook to a1, bishop goes anywhere, Rook to a8 and wham!

I don't do well when you have to assume a bad move in response

good review/instruction....

Ra1 then black play Be4 cover the a8 square ( if Kxe4 its a stalemate ). Ra8 check and Bxa8 took the rook with wham!

not impressive.

Rf1 is also a good move and same numbers of moves to achieve target

Rf1, Bf5, and mate is prevented for a couple more moves...

Nice lesson on how to box in a peice using two knights.  It's in the vault.

Why not Rh1 first?

Rh1 Bg8 Rh8 Stalemate, other moves possible, but not a mate in 2.

Of course! Thanks Icfseth, for your reply

good one, quite easy, but good