(A) almost supports the rehabilitation proposal, but the "unless" condition means it doesn't support either proposal. Because that condition was met—the buildings were a safety threat—(A) can't support rehabilitation. After knowing the buildings are a threat, (A) doesn't support any particular proposition. It doesn't bridge to either conclusion.

To be correct, (A) would either need to cut the "unless" condition, or add an additional condition explaining what to do if the buildings are a threat.

(B) is triggered by the stimulus: there are two proposals, and demolition would make it impossible to try rehabilitation. This is only true for demolition; if rehabilitation failed, we could still try demolition. (B)'s sufficient condition is met by the stimulus.

(B) also bridges to one of the two conclusions. The approach that doesn't foreclose the other approach should be adopted. This affirms the pro-rehabilitation conclusion: it doesn't foreclose demolition, so it should be adopted. (B) successfully determines that one of the two proposals should have been adopted.

(C) isn't triggered by the stimulus, so is not the correct answer. We don't know that only one of the proposals requires government funding. Rehabilitation would certainly require funding, but demolition might also require funding. It's never discussed, so it can't trigger this rule.

(D) doesn't lead to one of the two conclusions, so is not the correct answer. (D) only presents investigating alternatives as a necessary condition for demolition. Because of this, (D) can't actively support either conclusion. It could only eliminate the possibility of demolition, but couldn't affirm either demolition or rehabilitation.

(E) doesn't lead to one of the two conclusions, so is not the correct answer. It just explains that majority support is an insufficient reason to adopt one proposal over the other. That still doesn't tell us which proposal to choose, or what reasons would lead there.