The value(s) of the integral \(\mathop \smallint \limits_{ - \pi }^\pi \left| x \right|\cos nxdx,\;n \ge 1\) is
1
0 when n is odd and \( - \frac{4}{{{n^2}}}\) when n is even
2
\( - \frac{4}{{{n^2}}}\) when n is odd and 0 when n is even
3
0 for all values of n
4
None of the above