Which of the following sets of letters does not show lateral inversion?

When two mirrors are placed at an angle of $60^{\circ}$ to each other,how many images will be formed by them?

Two long plane mirrors $M_1$ and $M_2$ are kept inclined to each other. The angle between reflecting surfaces is $40^o$. $A$ light ray strikes mirror $M_1$ at an angle of $30^o$ with the normal. The maximum number of reflections the ray will undergo is:

$A$ plane mirror reflects a pencil of light to form a real image. Then the pencil of light incident on the mirror is

$A$ point source is placed at coordinates $(0,1)$ in the $xy$-plane. $A$ ray of light from the source is reflected on a plane mirror placed along the $X$-axis and perpendicular to the $xy$-plane. The reflected ray passes through the point $(3,3)$. What is the path length of the ray from $(0,1)$ to $(3,3)$?

Digital movie projectors work on the principle of