The correct answer is - A. There will be more rabbits and less grass in the region.
If the foxes are eliminated from the suggested ecosystem, the rabbits will lose their primary predator, and that will lead to a significant increase in their numbers. While the increase in number of the rabbits will be drastic, it will come a situation when that will no longer be possible as the food resources, the grass in this case, are limited. In that kind of scenario, the rabbits will engage into an interspecific, direct competition, as they will reduce the amount of grass significantly, thus not allowing their numbers the grow because they have over used the prime food resource.