If $z=\frac{4}{1-i}$, then $\bar{z}$ is (where $\bar{z}$ is complex conjugate of $z$ )

• A

  $2(1+i)$
• B

  $(1+i)$
• C

  $\frac{2}{1-\mathrm{i}}$
• Correct answer
  D

  $\frac{4}{1+\mathrm{i}}$

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