求教一道gwd-1-13

Q13:

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?

1. Florida attracts more people who move from one state to another when they retire than does any other state.


2. The number of people who move out of Florida to accept employment in other states has increased over the past ten years.


3. There are far more local businesses in Florida that cater to tourists than there are local businesses that cater to retirees.


4. The total number of people who retired and moved to another state for their retirement has increased significantly over the past ten years.


5. 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.


6. 答案是d。我想不明白，请教，谢谢。

Even though the the percentage who retired to Florida has decreased by three percentage, because the total number of people increase, the net effect is that there are could be more retiree moving to Florida.

At the begining, I was not sure I need to choose C or D.  After I took a second look, C actually is unrelated.