The answer is C. More offspring are produced than can survive.
Topography is the rise and fall of the land (AKA B)
The answer is C=territoriality
This is so because Al's cat may have seen another cat in his 'home'. Cats don't like it when other cats trespass into their territory, so this is a way of marking it.
The answer is D unrestricted whaling could lead to their extinction.
