Answer:
The correct answer is C. all natural resources
Step-by-step explanation:
C is correct answer because it refers to all the resources that could be used in that land, as a productional factor.
A is not correct, because ground not covered with water doesn't have to imply that it's used for production.
It is the same with B, because it doesn't mean that all the resources are being used there.
D is wrong as the land not only being used for farming.