$A$ person cannot see objects farther than $12\, m$ from the eye clearly. Name the defect of vision he is suffering from and the lens that should be used for correction of this defect. Illustrate with the help of a diagram,how this lens will correct the defective vision?

(N/A) The person is suffering from Myopia (near-sightedness),as they cannot see distant objects clearly beyond a certain point ($12\, m$ in this case).
The corrective lens to be used is a Concave Lens (diverging lens).
$A$ concave lens diverges the incoming light rays from a distant object,making them appear to originate from the person's far point $(12\, m)$. This allows the eye lens to focus the image correctly on the retina.
The diagrams are as shown in the provided image.