Answer:
D
Explanation:
Whatever answer you think it should be, the answer must exclude 0.
1/x = 1/0 which is undefined.
D is the only possible answer. None of the others make that exclusion. There is one other thing to consider: do any of the others exclude 0.
More importantly, what have you been told about the natural numbers. Some people include 0 in what the natural numbers are. Does your teacher or your instructions?
The whole numbers include 0. Without the restriction (3) is not the answer.
If it does, then that is not an answer. I think that D is the safest answer.