请教两个逻辑问题

lovebird0401

请教牛牛们两个逻辑问题，新东方的老师答得不清不楚的。。。

1、Although most smoking-related illnesses are caused by inhaling the tar in tobacco smoke, it is addiction to nicotine that prevents most smokers from quitting. In an effort to decrease the incidence of smoking-related illnesses, lawmakers in Sandonia plan to reduce the average quantity of nicotine per cigarette by half over the next five years. Unfortunately, smokers who are already addicted to nicotine tend to react to such reductions by smoking correspondingly more cigarettes.
The information above most strongly supports which of the following predictions about the effects of implementing the Sandonian government's plan?
A. The average quantity of tar inhaled by Sandonian smokers who are currently addicted to nicotine will probably not decrease during the next five years.
B. Sandonian smokers who are not already addicted to nicotine will probably also begin to smoke more cigarettes during the next five years than they had previously.
C. The annual number of Sandonian smokers developing smoking-related illnesses will probably decrease during the next five years.
D. The proportion of Sandonians attempting to quite smoking who succeed in that attempt will probably decrease during the next five years.
E. The number of Sandonians who quite smoking during the next five years will probably exceed the number who quite during the last five years.
 
为什么选C不选A？

2、In the United States, of the people who moved from one state to another when they retired, the percentage who retired to Florida has decreased by three percentage points over the past ten years. Since many local businesses in Florida cater to retirees, this decline is likely to have a noticeably negative economic effect on these businesses.
Which of the following, if true, most seriously weakens the argument?
A. Florida attracts more people who move from one state to another when they retire than does any other state.
B. The number of people who move out of Florida to accept employment in other states has increased over the past ten years.
C. There are far more local businesses in Florida that cater to tourists than there are local businesses that cater to retirees.
D. The total number of people who retired and moved to another state for their retirement has increased significantly over the past ten years.
E. The number of people who left Florida when they retired to live in another state was greater last year than it was ten years ago.
 
为什么选D不选A?

谢谢！