[(J ⊃ K) • (K ⊃ L)] ⊃ (∼L ⊃

Multiple Choice

[(J ⊃ K) • (K ⊃ L) ] ⊃ (∼L ⊃ ∼J)
Which of the following propositions is a proper assumption for conditional proof to prove that the above wff is a logical truth of PL?

A) [(J ⊃ K) • (K ⊃ L) ] ⊃ (∼L ⊃ ∼J)
B) [(J ⊃ K) • (K ⊃ L) ] ⊃ ∼L
C) (J ⊃ K) • (K ⊃ L)
D) J ⊃ K
E) J