Let $Z$ denote the set of integers define $f : Z \to Z $ by $ f(x) = \begin{cases} \frac{x}{2}, & \quad \text{x} \text{ is even}\\ 0, & \quad \text{x} \text{ is odd} \end{cases}$ <br> then $f$ is :

Question

( A ) neither one-one nor onto
( B ) one-one bit not onto
( C ) one-one and onto
( D ) onto but not one-one