bugcat: I found it amusing that I had an entirely separate set of candidate moves in mind when viewing this position. Here they are.
For comparison, I've left Dieter's candidates as x, y and z.
Dieter: I should note that my choice of alternatives in the problem series is 1) the blue move 2) my own move, which is a mistake 3) another mistake, clearly worse than the blue move. I never include options that are only slightly worse than the blue move. CHeers!
bugcat: Thanks for the clarification.