Data Sufficiency

Using Statement 1 alone, if '1' is in the set, then from rule i), we can deduce that -1 is in the set. But then using rule ii), we can't generate any new values besides 1 and -1. So there are only two values, 1 and -1, that we can be certain are in the set, and we have no way to know if -4 is in the set.

Using Statement 2 alone, if '2' is in the set, then from rule i), we know that -2 is in the set, and then since 2 and -2 are both in the set, from rule ii) we know (2)(-2) = -4 is in the set. So Statement 2 is sufficient alone.