I didn’t know that Joe had to get up early, so I didn’t wake him up.
A. If I had known that Joe had to get up early, I would have woken him up.
B. Provided that I had woken Joe up, I would know that he had to get up early
C. Much as Joe had been woken up, he would have to get up early.
D. Unless I had known that Joe had to get up early, I would have woken him up.