What is(are) the main reason(s) the tropics are warmer than the poles? select one: a. when sunlight hits the equator, it passes through less atmosphere, thus losing less energy than it does when it passes through more atmosphere at the poles. b. the poles are significantly farther away from the sun than the equator, thus receiving less solar energy. c. the sun's rays hit the earth directly at the equator but hit the poles at an angle; this concentrates the solar energy over a smaller area at the equator than at the poles. d. only the first and second choices are correct. e. all of the above choices are correct?