A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle `theta`, the spot of the light is found to move through a distance y on the scale. The angle `theta` is given by

Options

A. `frac(y)(x)`
B. `frac(x)(2y)`
C. `frac(x)(y)`
D. `frac(y)(2x)`