In the 1960s, surveys of Florida's alligator population indicated that

I want to share some of my thoughts for the option (A) and (E). The former was not an obvious winner to me when I did this question the first time, while the latter was tempting because it resembled the correct answer to the "mountain lion" CR question.

Premise: Over the course of the 1990s, reports of alligators appearing on golf courses and lawns increased dramatically.

Conclusion: Therefore, in spite of whatever alligator hunting went on, the alligator population must have increased significantly over the decade of the 1990s.

Let's check the option (A):
A. The human population of Florida increased significantly during the 1990s.

Several experts have pointed out that if the human population increased significantly, it is likely that at least some sightings occurred because there are more people around to see the alligators. I can understand this line of thinking, but I have to say that the connection is not very persuasive because of the modifier "reports of alligators appearing on golf courses and lawns." They are not reports of sighting in rivers or lakes, places anyone can be, but reports of sighting at golf lawns, places where only the member of golf clubs can be.

Maybe in some places in the US, it is reasonable to infer that the rise in human population would likely lead to a rise in the number of golf players, but that is not the case in most Asian countries (in my opinion). Here, the rise in human population would likely lead to growths in the number of new buildings or the number of gym customers, but golf players? Not really....

I do not reject (A), though. As some experts have pointes out, the option (A) could be two-pronged. Even though I dislike the connection mentioned above, I could understand that a significant growth in human population usually triggers environmental disruption and thus some alligators' habitats might have been destroyed. So, it is possible that the alligators were displaced and entered the golf areas, or it could be the case that the alligators never left the river they stay but their habitats were just turned into golf lawns.

Let's check the option (E):
E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns.

This is similar to the correct answer of the mountain lion question but is the incorrect answer to this one......perhaps the GMAC was trying to prove its diversity and creativity when making this question.

The option (E), while tempting, is incorrect for two reasons:
(1) It says "few people," compared with a single person in the mountain lion quesiton. Even if we apply the logic in the mountain lion question that the others can help correct the mistaken belief, it does not work here. There were "few people" in most of the sightings, so if one of them were to mistakenly believe that he or she saw an alligator, the others could help correct the mistaken belief. So, we cannot really use the logic in the mountain lion case to doubt the accuracy of the reports in this alligator case.

(2) Alright, even if we decide to ignore the logic in the mountain lion case and make our own assumption that few people can be mistaken together about what they see (after all, it is not a crazy assumption), the option (E) might be able to suggest the accuracy of most of the reports is doubtful.

But, the premise says that "reports of alligators...... increased dramatically." The modifier "dramatically" plays a role here. The word "dramatically" means double-digit growth or even rise of multiple times.

Let's say that there were 100 reports before and the number of reports grew to 150 (at least) in the 1990s. Even if we take an extreme move, thinking that most of the sightings, or 80 to 90, were false or mistaken, there were still many reports of sightings in which many people were present. These reports should be more likely accurate. Now, the option (E) could not attack the accuracy of these reports. And these reports could still support the conclusion that the alligator population have increased.