How is radiation related to electromagnetic waves and thermal energy?

Well, radiation, in terms of physics, is the emission of electromagnetic waves

now, electromagnetic waves can take many different forms like visible light, radio waves,  gamma radiation, ultraviolet light. Depending on its wavelength or frequency

thermal energy or heat generally takes the form of infrared light and all light is an form of electromagnetic wave

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.