Answer
Please see the work below.
Work Step by Step
(a) We know that the farsighted person uses converging lenses glasses. The convex lens focuses the light from an object inside the near point to form an image that is beyond the near point. Thus, the farsighted person's glasses are used to start the fire.
(b) We know that the best explanation is option (II) -- that is, a farsighted person can't focus on close objects, so the glasses to correct that person's vision are converging. A converging lens is what you need to concentrate the rays of the Sun.