The image of an object is formed on the (d) Retina. The retina is a light-sensitive layer of tissue lining the inner surface of the eye, located at the back of the eye behind the lens. When light enters the eye through the cornea and lens, it is focused onto the retina.
The retina contains specialized photoreceptor cells known as rods and cones, which detect light and convert it into electrical signals. These signals are then transmitted to the brain via the optic nerve for visual processing.
The image formed on the retina is inverted and reversed due to the optics of the eye. However, the brain processes this information and interprets it correctly, allowing us to perceive a correctly oriented image of the object.

While the pupil controls the amount of light entering the eye and the cornea and iris play roles in focusing light onto the retina, it is the retina where the actual image of the object is formed and detected.