Option 1: Its focal length is zero.

This statement is incorrect. A plane mirror does not have a focal length. The concept of focal length is applicable only to curved mirrors.

Option 2: The size of the image of an object placed in front of the mirror is slightly less than that of the object.

This statement is incorrect. The size of the image formed by a plane mirror is always equal to the size of the object. The mirror reflects light rays in such a way that the image appears to be behind the mirror at the same distance as the object is in front of it.

Option 3: The image is virtual, erect, and laterally inverted.

This statement is correct. When an object is placed in front of a plane mirror, the mirror reflects the light rays and forms an image that cannot be projected onto a screen. This image appears to be behind the mirror and has the same size as the object. The image is also upright (erect) and appears to be flipped horizontally (laterally inverted).

Option 4: Its focal length is 200 cm.

This statement is incorrect. A plane mirror does not have a focal length. The concept of focal length is applicable only to curved mirrors.

Therefore, the correct statement for a plane