A set is defined recursively as follows:

1. Basis step: (1∈S)∧(3.5∈S)(1∈S)∧(3.5∈S)(1 \in S) \wedge (3.5 \in S)

2. Recursive step: if x∈Sx∈Sx \in S, then (x+1)∈S(x+1) \in S.

Which of the following is the best statement that describes SS?