Answer : The correct option is (A) "12 inches"
Explanation :
It is given that, a 12-inch object is placed 30 inches in front of a plane mirror. A ray of light from the object strikes the mirror at a 45-degree angle ( from fig) .
In case of plane mirror, the size of image is exactly same as that of size of object.
So, we can say that the size of image produced by the plane mirror is 12 inches.
Hence, the correct option is (A) i.e. 12 inches.