A converging mirror is placed on the right hand side of a converging lens as shown in the figure. The focal length of the mirror and the lens are $20 \mathrm{cm}$ and $15 \mathrm{cm}$ respectively. The separation between the lens and the mirror is $40 \mathrm{cm}$ and their principal axes coincide. A point source is placed on the principal axis at a distance $d$ to the left of the lens. If the final beam comes out parallel to the principal axis, then the value of $d$ is:

• A

  $4 \mathrm{cm}$
• B

  $8 \mathrm{cm}$
• Correct answer
  C

  $12 \mathrm{cm}$
• D

  $16 \mathrm{cm}$

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