A person suffering from short-sightedness can see clearly only up to a distance of 2 meters. Find the nature and power of the lens required to correct his vision.
a) Convex lens, power = +0.5 D
b) Concave lens, power = -0.5 D
c) Convex lens, power = -0.5 D
d) Concave lens, power = +0.5 D
