Task: Question Generation
Input (English): Background Paragraph: Solar radiation (or sunlight) is the energy Earth receives from the Sun. Earth also emits radiation back into space, but at longer wavelengths that we cannot see. Part of the incoming and emitted radiation is absorbed or reflected by the atmosphere. In May 2017, glints of light, seen as twinkling from an orbiting satellite a million miles away, were found to be reflected light from ice crystals in the atmosphere. 
Story: Mark was studying the effect of Sun's radiations on Earth. To that end, he studied Sun's radiations, which he labeled as rad A. Then he studied Earth's radiations, which he labeled as rad B. He also learned that longer wavelength radiations would produce heat.
Output (English): Which radiation is not visible, rad A or rad B?