[求助] OG 114 Guidebook writer

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?

A. 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.
B. Hotels built since 1930 can generally accommodate more guests than those built
before 1930.
C. The materials available to carpenters working before 1930 were not significantly
different in quality from the materials available to carpenters working after 1930.
D. The better the quality of original carpentry in a building, the less likely that
building is to fall into disuse and be demolished.
E. The average length of apprenticeship for carpenters has declined significantly
since 1930.

我选的是A. D选项我也可以理解。但是不知道A为什么错。
A选项中说1930年以前的酒店质量远远好过1930年以前别的房子质量。那就说明并不是不同时期的木匠技术的问题，因为同一时期相同的木匠造出来的不同房子中这些酒店的质量就是好，那说明是有别的原因导致了这些酒店可以比较完好地保存到现在。所以对原文构成了削弱。我不认为是无关。不理解啊，求解释...