Final answer:
The chronic eye condition caused by a severely clouded lens is a cataract (option c). It scatters light entering the eye, leading to impaired vision. Laser surgery for eye repairs requires parallel rays for precise focusing onto the retina.
Step-by-step explanation:
A severely clouded lens causes the chronic eye condition known as cataract. Cataracts involve the clouding of the lens within the eye which obstructs and disperses light entering the eye, leading to impaired vision. Cataracts are responsible for many cases of blindness and can significantly reduce a person's quality of life. The lens's clarity is vital for proper vision because it helps to focus light onto the retina at the back of the eye. A clear lens allows light to pass through it and focus correctly, but when a lens is clouded by a cataract, it scatters the light, which then can't be focused sharply, and vision becomes blurry.
In terms of eye surgeries, such as repairing a tear in the retina with laser, the rays entering the eye must be parallel. This ensures that they are focused precisely onto the retina after passing through the corrective measures of the eye's lens system, whether it be through natural focusing by a relaxed normal-vision eye or by the use of a diverging lens in cases where corrective action is needed.