I agree with Jurgen. It's surrounded by much flatter land. If the land below it is flatter, then it will definitely look bigger, making it easier to see from miles away. A does not make sense because it does not matter what the pollution levels are. Pollution does not make it more visible or invisible. C does not make sense because if that was true, then it would look smaller from a ways away, making it harder to see from miles away. Not easier. D does not work because the population around that area does not have a big affect on wheather or not you can see it. Once again, your answer is B) It is surrounded by much flatter land.
~Silver