Mica Goes Swimming Only If Nicole Lifeguards

Multiple Choice

Mica goes swimming only if Nicole lifeguards. Pedro is free on the condition that Ona goes to the beach. Mica goes swimming unless Ona goes to the beach. Nicole doesn't lifeguard. So, either Pedro is free or Mica goes swimming.
-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) MP
B) MT
C) HS
D) Conj
E) Add