再次请教GWD4-14

Q14:

Guidebook writer: I have
visited hotels throughout the country and have noticed that in those
built before 1930 the quality of the original carpentry work is
generally superior to that in hotels built afterward. Clearly
carpenters working on hotels before 1930 typically worked with more
skill, care, and effort than carpenters who have worked on hotels built
subsequently.

Which of the following, if true, most seriously weakens the guidebook writer’s argument?

1. The
   quality of original carpentry in hotels is generally far superior to
   the quality of original carpentry in other structures, such as houses
   and stores.
           
2. Hotels built since 1930 can generally accommodate more guests than those built before 1930.
           
3. The
   materials available to carpenters working before 1930 were not
   significantly different in quality from the materials available to
   carpenters working after 1930.
           
4. The
   better the quality of original carpentry in a building, the less likely
   that building is to fall into disuse and be demolished.
           
5. The average length of apprenticeship for carpenters has declined significantly since 1930.

因此削弱了并不是以前的木匠手艺高，而是只有高水平的才保留住了。

但是选项并没有说只有1930年前的房子才这样吧？那么30年之后的房子也有可能因质量差而被废弃，而即使在同样都有被弃的可能性之下，仍然是30年前的房子质量好些，那不就加强结论了吗，或者至少没有削弱结论啊

纠结中，等待高手解惑....