shangcailanru

B) is wrong because the argument is about the quality of the carpentry work, not the capacity of the accomodation.

D) simply points out that whateve building left standing HAD better quality of orginal carpentry to begin with. It is similar to the evolution theory: ONLY the better or the best would survive. Thus, you cannot judge the quality of originals based on the leftovers. The leftovers are not representative of the original.

shangcailanru

为了capacity 而牺牲了quality??

The passage has not talked about this.  You cannot inject your own thoughts into the passage.  As far as we know, capacity has nothing to do with qualify (according to the passage and/or choice B).