The idea:

We notice that in the current position the Black King is pinned. We also notice that White could win in 1 move with Bishop D4-B6 or D4-F6, if only the Black Knight was not in D5, so defending both B6 and F6...

But, since, the Black King is pinned, if White could move so to force Black to move its Knight, i.e. while keeping the Black King pinned, and also keeping its own Bishop now in B4 ready to strike regardless of where the Black Knight gets moved...

The solution:

D4-F2: this is the only position where the White Bishop stays out of reach of the Black Knight but remains ready to strike;
D5-any allowed: Black is forced to move its Knight;
F2-B6 or, if the Black Knight is now in C7, F2-H4.

The idea:

We notice that in the current position the Black King is pinned. We also notice that White could win in 1 move with Bishop D4-B6 or D4-F6, if only the Black Knight was not in D5, so defending both B6 and F6...

But, since, the Black King is pinned, if White could move so to force Black to move its Knight, i.e. while keeping the Black King pinned, and also keeping its own Bishop now in B4 ready to strike regardless of where the Black Knight gets moved...

The solution:

D4-F2: this is the only position where the White Bishop stays out of reach of the Black Knight but remains ready to strike;
D5-any allowed: Black is forced to move its Knight;
F2-B6 or, if the Black Knight is now in C7 or E3, F2-H4.