A $3 \times 3$ matrix $P$ is such that, $P^{3}=P$. Then the eigenvalues of $P$ ܲ are

1. $1, 1, −1$
2. $1, 0.5 + ݆j0.866, 0.5 − ݆j0.866$
3. $1,−0.5 + ݆j0.866, −0.5 − ݆j0.866$
4. $0, 1, −1$