What step occurred first in the evolution of life?

A) formation of lipid spheres
B) formation of protein-RNA systems
C) formation of membrane-bound protocells
D) self-assembly of organic monomers
E) formation of ATP

The self-assembly of organic monomers, such as amino acids and nucleotides, into more complex molecules such as proteins and RNA, was likely the first step in the evolution of life. This step led to the formation of the first self-replicating systems, which eventually gave rise to the first living organisms. The other options, such as the formation of lipid spheres and membrane-bound protocells, likely occurred later in the evolution of life as these structures require more complex processes and molecules. The formation of ATP is an important step in cellular metabolism, but it likely occurred after the formation of self-replicating systems.