If J 0, what is the value of J ?

QUESTION YOU ARE TALKING ABOUT SHOULD READ:
If \(J\neq{0}\), what is the value of \(J\) ?

(1) \(|J| = J^{-1}\)
(2) \(J^J = 1\)

Two reasons why should the stem state that \(J\neq{0}\):
For statement (1) if \(J=0\) then we'll have \(0^{-1}=\frac{1}{0}=undefined\). Remember you can't raise zero to a negative power.
For statement (2) if \(J=0\) then we'll have \(0^0\). 0^0, in some sources equals to 1, some mathematicians say it's undefined. Anyway you won't need this for the GMAT because the case of 0^0 is not tested on the GMAT. So on the GMAT the possibility of 0^0 is always ruled out.

Also notice that saying in the stem that J is an integer is a redundant.

AS FOR THE SOLUTION:
If \(J\neq{0}\), what is the value of \(J\) ?

(1) \(|J| = J^{-1}\) --> \(|J|*J=1\) --> \(J=1\) (here J can no way be a negative number, since in this case we would have \(|J|*J=positive*negative=negative\neq{1}\)). Sufficient.

(2) \(J^J = 1\) --> again only one solution: \(J=1\). Sufficient.

Answer: D.