Farsightedness is corrected by using:

Correct option is D

Farsightedness, or hyperopia, is corrected by using convex lenses. These lenses converge light rays before they enter the eye, helping focus the image on the retina for clear vision at a distance.
Explanation of options: (a) ✘ Incorrect. Cylindrical lenses are used for astigmatism, not farsightedness. (b) ✘ Incorrect. Bifocal lenses are used to correct both nearsightedness and farsightedness, but convex lenses specifically address farsightedness. (c) ✘ Incorrect. Concave lenses are used for nearsightedness (myopia), not farsightedness. (d) ✔ Correct. Convex lenses help focus light properly onto the retina for those with farsightedness.