The human eye forms the image of an object at its

The correct answer is (d), the retina. The retina is a light-sensitive tissue at the back of the eye that converts light into electrical signals that are sent to the brain. The brain interprets these signals as images.

The cornea is the clear front part of the eye that helps to focus light onto the retina. The iris is the colored part of the eye that controls the amount of light that enters the eye. The pupil is the black opening in the center of the iris that allows light to enter the eye.

The cornea, iris, and pupil are all important parts of the eye, but they do not form the image of an object. The retina is the only part of the eye that can form an image.