Trouble understanding puzzles

I've been working on the training puzzles a bit and every once in a while I run into a puzzle that doesn't seem to make any sense, yet when I analyze it with the engine it seems to agree with the seemingly vague solutions. In this example (lichess.org/training/61864) how is it obvious that d5 is the "best" move? I've run into a few other stumpers that seemed even more arbitrary but this was just the most recent.

You've got to look at all the direct forcing moves; remember the aphorism, "pinning is winning". Here you have a piece in an absolute pin that you can attack with a pawn, hence it screams to be played. In general if you can establish a long-term pin you can pile up pressure onto it. Hope that helps, and Good Luck with your future puzzles.