The correct option is C Chemotrophs
In the reducing environment of primitive Earth, large molecules such as amino acids and nucleic acids were formed from simple molecules. Under the influence of UV light and electrical discharges, polymers such as proteins and nucleic acids were formed. These in turn led to the origin of the first cellular forms of life. Since the surface of Earth was continuously bombarded with UV rays, life on the surface was impossible. Hence, the first life adapted to exist deep in the ocean and derived energy from what was available on earth then, which were chemicals. They were thus, anaerobic chemotrophs. Most of them were also extremophiles, surviving in extreme conditions.