explain why please type the words dont write on the paper, I cant see clearly

9. (10 points) A solar cell must have antireflection coating that is made up of multilayers of some materials. The layers are made of the same materials as long as they satisfy: a) having smooth interfaces b) having each layer of quarter wavelength c) it is determined by the voltage of the cell d) antireflection coating are not used here e) none of the above 10. (10 points) In an laser, a two-level system (atom or molecule) works better than a 3 or 4 level system because: a) it is easier to establish population inversion b) 2-level is cheaper than 3 or 4 level material C) 2-level needs less energy to be pumped d) 2-level is more efficient material e) none of the above Bonus (15 pts): A diode emitting 500 mW at 370 nm and one emitting 500 mW at 900 nm. Which diode appears brighter to your eye? Why