The key results explain how you'll achieve a certain goal. They have to be quantitative, but always measurable in terms of their progress. This has to be considered when it comes to key results, because only results count for each milestone on the way to achieving the goal in question.
Radio waves have the lowest energy, but the longest wavelength. So radio waves is the answer. Good luck on the rest and message me for more help.
33 - 15 = 18
This element is P-33