I Know Something If, and Only If, I Have Some

Multiple Choice

I know something if, and only if, I have some causal contact with the physical world. If I know something, then there is no demon deceiver. I know something. So, I know something just in case both I have causal contact with the physical world and there is no demon deceiver.
-Working backward from the conclusion of this argument, which of the following is the most likely justification of the last step of the derivation?

A) BMP
B) BMT
C) BAssoc
D) BHS
E) Equiv