Which of the following forms of energy is thought to have been involved in the production of large organic molecules in the primitive reducing atmosphere?

A) radioactivity
B) electrical energy
C) heat
D) radiation from the sun
E) All of the answer choices describe forms of energy that could have contributed to the production of large organic molecules on early Earth.

All of the answer choices could have potentially contributed to the production of large organic molecules in the primitive reducing atmosphere on early Earth. Radioactivity and heat from the Earth's core could have provided energy for chemical reactions, electrical energy could have been generated by lightning, and radiation from the sun could have contributed to the energy input as well. Therefore, it is likely that a combination of these energy sources contributed to the production of large organic molecules during early Earth's history.