JetBlue Buys Planes If and Only If Both Delta Does

Multiple Choice

JetBlue buys planes if and only if both Delta does not advertise a sale and Southwest does not expand routes.

A) J ≡ ∼(D • S)
B) J ⊃ (∼D • ∼S)
C) J ≡ (∼D • ∼S)
D) ∼(D ∨ S) ⊃ J
E) J ∨ (∼D • ∼S)