Final answer:
Sharp vision in good illumination is primarily provided by: cones (Option B). They are responsible for color vision and operate best in bright light. The lens and cornea focus light on the retina, and the iris adjusts light intake.
Step-by-step explanation:
Sharp vision in good illumination is provided by cones. Cones are one of the two types of photoreceptors found in the retina of the human eye.
While rods are more numerous and provide vision in low light environments, they only detect shades of gray.
In contrast, cones are responsible for color vision and work best in bright light. They are concentrated in the fovea, the area of the retina where vision is the sharpest.
The role of the lens of the eye is to focus light rays onto the retina to form clear images. It changes shape to bend light by the right amount needed for focusing.
The cornea also helps in the focusing process but is primarily a protective layer on the front of the eye. The iris adjusts the amount of light coming into the eye through the pupil.
Hence, the correct answer is: cones (Option B).