The eye is a complex organ that allows us to see the world around us.
In order for us to have clear vision, light must be accurately focused onto the retina, which is located at the back of the eye.
Out of the options you provided, the eye defect that is caused by the inability of the eye to focus light on the retina is Myopia, also known as nearsightedness.
Myopia occurs when the eye is too long or the cornea (the clear front part of the eye) is too steep, causing light to be focused in front of the retina instead of directly on it.
This results in distant objects appearing blurry or out of focus, while nearby objects can still be seen clearly. To put it simply, in myopia, the eye is like a camera that is unable to properly focus the light onto the film.
Instead, the light falls short and focuses in front of the film, resulting in a blurry image. It's worth noting that myopia is a very common eye condition and can be corrected with the use of glasses, contact lenses, or even laser eye surgery.
These corrective measures help to redirect the incoming light so that it is properly focused onto the retina, allowing clear vision.
So, in summary, the eye defect caused by the inability to focus light on the retina is Myopia (nearsightedness).