If $a=\operatorname{Im}\left(\frac{1+z^2}{2 i z}\right)$ and $z$ is any non zero complex number such that $|z|=1$, then $a=$

• A

  $\operatorname{Re}(z)$
• B

  $\operatorname{Re}(z) \operatorname{Im}(z)$
• Correct answer
  C

  $-\operatorname{Re}(z)$
• D

  $\operatorname{Re}(z)+\operatorname{Im}(z)$

Hence, the correct answer is option: 'C'.