As the object moves from infinity to focus, then which is true, about the image formed by a single a concave mirror?

detailed solution

Correct option is B

As the object moves from infinity to centre of curvature, the image formed by a concave mirror would be real and is moving from focus to centre of curvature, but as the object crosses centre of curvature and moves towards focus the image is still real but moves from centre of curvature towards infinity and when the object is at focus the real image would be formed at infinity. So, image speed is smaller in beginning when the object is moving from infinity to centre of curvature and increases thereafter.