Bishop

c5 sacrifice. This opens up c4 for bishop, and opening the d-file for white.

f6 forces black to Bh8, and thereby traping the bishop.

Bxd5 simply because retreat doesn’t seem to be that good for black bishop.

Bd4 makes the best use of black bishop, and giving black control over a7-g1 diagonal. After Bd4, the bishop is relatively secure without fear of being chased away by any pawns.

There two equally good options.
Case 1: Bf4, giving black control over the center, and h2-b8 diagonal.
Case 2: Bishop on g2 is living below its potential. e4 help to reduce to clutter in the h1-a8 diagonal.

White see the threat of allow black having control over a8-h1 diagonal. To prevent this from happening, …Be3 to preempt e4-e3 by black.