The answer would have to be the third option "huge." When I was a kid, my family rented a small house Florida. It was a short walk down a weed-choked path to the small lake where my sister and I liked to go fishing. One day, just as the sun rose above the trees, we walked down the path and realized our way was blocked by a fallen tree. As we approached, the tree moved. This was no tree, this was a huge alligator. We had seen small alligators now and then, but nothing like this.
You can tell because if you read on you will see 'We had seen small alligators now and then, but nothing like this.' Using context clues you can see that this alligator was bigger than the other alligators the child had seen.
Hope this helps!