Why are there two parallel plane mirrors in a barber shop?A. Two parallel plane mirrors from infinite imagesB. The customer can see the image of the back of his head with the help of this setup.C. The setup focusses light and helps the barber to cut the hair better.D. None of the above.

A. Two parallel plane mirrors form infinite images.

The two parallel plane mirrors in a barber shop are typically placed to create a series of infinite reflections. This allows customers to see multiple images of themselves from different angles, including the back of their head, which helps them gauge how their haircut is progressing. It is not primarily for focusing light or for the barber to cut hair better, but rather for the convenience and satisfaction of the customer.