(A) establishes the two bridges we’re looking for. First, if it’s helpful to someone, then it’s laudable. This shows that passing along Sara’s number would be laudable (because a premise tells us that it’s helpful). Second, if you have not led someone to believe you’d do it, then an action is not wrong. This shows not passing along the number is not wrong (because we know the Jacksons didn’t lead Sara to think they’d pass along the number).

We’re trying to prove that one action is laudable, and that failure to do the action is not wrong. But (B) tells us that IF we know an action is not wrong, then that action is laudable. We don’t know as a premise that an action is not wrong; we’re trying to prove that it’s not wrong.

We’re trying to prove that one action is laudable, and that failure to do the action is not wrong. But (C) is designed to prove that one action is both laudable and not wrong. This doesn’t address whether NOT doing the laudable action is not wrong.

We’re trying to prove that one action is laudable, and that failure to do the action is not wrong. But (D) tells us that IF we start off knowing an action is laudable, then it’s difficult and not wrong. This structure can never help us prove that an action is laudable, because it puts “laudable” on the sufficient condition side of the principle.

We’re trying to prove that one action is laudable, and that failure to do the action is not wrong. But (E) tells us that IF we start off knowing that an action is laudable, then that action would not be wrong to refrain from doing. This structure can never help us prove that something is laudable, because it puts “laudable” on the sufficient condition side of the principle.