(N/A) $(i)$ The defect of vision represented is Hypermetropia (farsightedness).
$(ii)$ The two possible causes of this defect are:
$(a)$ The eyeball has become too short,so that light rays from a nearby object are focused at a point behind the retina.
$(b)$ The focal length of the eye lens is too long,meaning the ciliary muscles are unable to make the lens sufficiently convex to focus the image on the retina.
$(iii)$ This defect can be corrected by using a convex lens of appropriate power. The convex lens converges the incoming light rays before they enter the eye,allowing the eye lens to focus the image exactly on the retina,as shown in the diagram.