Answer
(a) positive
(b) I
Work Step by Step
(a) We know that the power of corrective glasses should be positive because in order to view nearby objects, we need converging lenses as the intraocular lens cannot change its focal length to focus at closer distances.
(b) We know that the best explanation is option (I) -- that is, the refractive power should be positive (converging) because the intraocular lens will make the person farsighted.