Let $f$:$\{1,2,3,4\}Z$ with $f(x)=$xmod$2.$ Which one of the following statements is true?

$2$ is the only pre$-$image of $0$

$2$ and $4$ are the only pre$-$images of $0$

$4$ is the only pre$-$image of $0$

$1,2,3$ and $4$ are all pre$-$images of $0$