In the United States of the people who moved from one state to another

NikhilJose, it is important to keep in mind that we need a florida now vs florida previous comparison.

Looking at option C -
The reduction for florida has been in terms of percentage of the total people moving. Let's say that the total number of people moving is 10,000,000 and out of those 43% move to florida, i.e, 4,300,000. But the percentage has changed to 40% (3% reduction).

Now, option C says that the total number has increased significantly. Let's say 10,000,000 has become 20,000,000. Now 40% of 20,000,000 will go Florida. So 8,000,000 will go to Florida, resulting in an increase in the total number moving to florida. This would actually support those local businesses and hence, weakens the stem.
Of course the figures can be switched around, but this is definitely a serious weakner.

Coming to your point, not it is not an absolute fact that people moving to Florida would increase. You could come up with a figure that shows that the total number moving to florida has decreased, but there is a good chance that it may increase. But the point is, this option is looking at the right place.

Option E - this option is comparing florida to other states in terms of pure numbers (like you've correctly pointed out), but it does not really weaken the statement as we're looking to compare florida today vs florida in the past. That is not to say if the option is true, the statement is strengthened, but it is not attacking the right comparison.

Hope this helps!