Final answer:
Insolation refers to the solar radiation that reaches the Earth's surface and consists of both direct and diffuse radiation. It is not the only energy input driving Earth's atmospheric system.
Step-by-step explanation:
Insolation refers to the solar radiation that reaches the Earth's surface. It consists of both direct radiation, which travels in a straight line from the Sun to the Earth, and diffuse radiation, which is scattered by the atmosphere and clouds before reaching the surface. Therefore, both options B) It consists of diffuse radiation, and C) It consists of direct radiation are true. However, option A) It is the only energy input driving Earth's atmospheric system is not true, as there are additional non-solar inputs like geothermal and tidal energy. So, the correct answer is option E) None of the above are true.