To help Maria see Sandy when he is out on the ocean riding a wave, she would need prescription sunglasses with the appropriate power. Since she can see Sandy clearly only when he is standing closer than 2.0 meters, the power of her prescription sunglasses would depend on correcting her vision for viewing objects at a greater distance.
a) Maria would need prescription sunglasses with a negative power (to correct for farsightedness) so that she can see Sandy when he is farther away. The power required would be based on her specific vision needs and how far she wants to be able to see clearly.
b) The type of lenses her glasses would contain depends on her vision condition. If Maria is farsighted, the lenses in her sunglasses would be concave (diverging) to help focus light properly on her retina, enabling her to see distant objects clearly. These lenses would be designed to counteract the inability of her eyes to bring distant objects into focus, allowing her to see Sandy out on the ocean even when he is far away.
