Alens is transparent material with
a) two flat surfaces that can reflect light
b) one or two curved surfaces that can reflect light
c) one or two curved surfaces that can refract light
d) two flat surfaces that can refract light

I think the correct answer from the choices listed above is option C. A lens is transparent material with one or two curved surfaces that can refract light. A lens is made of a transparent material having an index of refraction of 2.0. One side of the lens is flat, and the other convex with a radius of curvature of 25 cm.

Because its reliable.   there is no pollution  the chances of a radiation leak is low