LSAT Question

题真郁闷，先谢了

Saunders: Everyone at last week’s neighborhood association meeting agreed that the row of abandoned and vandalized houses on Cariton Street posed a threat to the safety of our neighborhood. Moreover, no one now disputes that getting the houses torn down eliminated that threat. Some people tried to argue that it was unnecessary to demolish what they claimed were basically sound buildings, since the city had established a fund to help people
in need of housing buy and rehabilitate such buildings. The overwhelming success of the demolition strategy, however, proves that the majority, who favored demolition, were right and that those who claimed that the problem could and should be solved by rehabilitating the houses were wrong.
20.  Which  one  of  the following principles, if established would determine that demolishing the houses was the right decision or instead would determine that  the  proposal advocated by the opponents of demolition should have been adopted?
(A)  When  what to do about an abandoned neighborhood building is in dispute, the  course  of  action [that would result in the most housing for people who need  it] should be the one adopted unless the building is believed to pose a threat to neighborhood safety.
(B) When there are two proposals for solving a neighborhood problem, and only one  of  them  would preclude the possibility of trying the other approach if the  first  proves  unsatisfactory, then the approach that does not foreclose the other possibility should be the one adopted.
(C)  If  one  of  two  proposals for renovating vacant neighborhood buildings requires  government funding whereas the second does not, the second proposal should  be the one adopted unless the necessary government funds have already been    secured.
(D)  No pain for eliminating a neighborhood problem that requires demolishing
basically  sound  houses  should  be  carried  out  until  all other possible
alternatives have been thoroughly investigated.
(E) No proposal for dealing with a threat to a neighborhood’s safety should
be adopted merely because a majority of the residents of that neighborhood
prefer that proposal to a particular counterproposal.

答案是B，有些不太理解，到底谁preclude the possibility of trying the other approach ，拆房的还是不拆的？