Convex Lenses and Farsightedness: Image Formation Explained

For a farsighted person, the eyeball is shorter than normal. This means that light rays coming from a distant object converge beyond the retina instead of on it. To correct this, a convex lens is used.

Convex lens converge the light rays and the image is formed before the retina. This allows the farsighted person to see clearly.

So the correct answer is B: before.