In my opinion, the answer can be explained like this.
Ferns are seedless plants possessing a developed vascular system. The true ferns have complex leaves (megaphylls) that contain more than one vein. This developed system allows ferns to exist in different terrestrial environments.
Moss have no vascular system and they are not capable to transport the water and nutrients from one part of the plant to another. Therefore, moss is found in moist environments and not in extreme environments.
Where did you come across this question? In a past year paper?
Book for Class 9 MCQs - I came across Class 9 MCQ books by KVS ZIET. They are good. Plus there are some more books available. Will you be in class 9 or 10 in 2015 April?