I would have worn the right shoes if I had known I was going to do all this climbing.
A.I would love to go climbing, but I do not have any shoes that would be suitable.
B.As I did not know I was going to do so much climbing, I did not wear suitable shoes.
C.I did not go climbing because I did not have the right shoes.
D.I would have gone on the climb if I had been wearing the right shoes.