Best move question

Hi all,

Earlier today I was playing a game on Chess.com against AI. To me it seems as moving the bishop on c4 to safety is a no-brainer, but the AI keeps suggesting castling king-side as being the best move at this point in time. Can someone help me explaining why that is?

Thanks a lot!

In this position white is behind in development and their king is very exposed. On the other hand, they do have an advantage in material. Castling moves the king to safety and develops the rook. After castling, 1 ... dxc4 2. exf3 Qxf3.

White's lost a pawn, but still has a material advantage. Black has three pawns on a single file and none of them can be protected by other pawns. They are a very easy to attack and hard to defend. 

In contrast, saving the B does nothing for white's development and king safety. It doesn't harm black's position in anyway, and it looses the e5 pawn with nothing gained in exchange.

1. o-o dxc4 2. exf6 Qxf6 and the centre is wide open with blacks king in the middle, the queen attacked and 3. Re1+ Kf8. Black would also have a terrible pawn structure with 3 pawn islands and triple isolated pawns on the c file. More generally, if black grabs your bishop you can regain the piece with exf6, open up the centre, secure your king, and bring your rook towards the e file.