I'm stuck on this question. Which domain can you not write a proof by induction. I'm leaning on my answer #2 because it has positive and negative integers in the same set.

Over which domain D is it NOT possible to write a proof by induction of a statement of the form for all n in D, P(n) where P(n) is a propositional function with domain D? O The set of integers greater than 7. O The integers {0,1,-1,2,-2,...} O The natural numbers {1,2,3,...} O The non-negative integers {0,1,2,...} O The set of integers greater than -1