请教这2到逻辑题目

jackabigail

1.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 ob 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 serious weaken the argument ?

D The better the quality of original carpentery in a building,the less likely that building is to fall into disuse and be demolished.   为什么选这个答案？

2.Mayor Delmont's critics complain about the jobs were lost in the city under Delmont's leadership. Yet the fact is that not only were more jobs created than were eliminated,but the average pay for these new jobs has been higher than the average pay for jobs citywide everyyear since Delmont took office.So there can be no question that throughout Delmont's tenure the average paycheck in this city has been getting steadily bigger.

Which of the foolowing if true most strengths the argument?

D The average pay for jobs eliminated in  the city during Mayor Delmont 's tenure has been roughly equal every year to the average pay for jobs citywide

为什么啊？谢谢指教