The correct option is D First formed cells
A protobiont is defined as an aggregate of abiotically produced organic molecules surrounded by non unit membrane. For example, Coacervates (the large spherical colloidal aggregates of macromolecules), microspheres (colloidal aggregates of protein bubbles) are protobionts. Protobionts were transformed into a first living prokaryotic organism with gradual improvement in metabolism, growth and reproduction. Thus, the correct answer is option D.