One of the accepted scientific theories describing the origin of life on earth is known as chemical evolution. according to this theory:

Explanation:

Life evolved from various chemical reaction that took place on the prebiotic Earth. According to this theory The conditions of prebiotic Earth favoured some chemical evolution that gave rise to a large number of organic molecules. These organic molecules were formed in anoxic and reducing conditions.After the synthesis of these organic matter the seas were converted in hot dilute prebiotic soup or primordial soup. This was then followed by the development of simplest physicochemical system which had characteristics of self organisation, regulation, perpetuation etc.

individual oxygen atoms are formed during photosynthesis.-c.

answer; synapse; i believe this is correct,plz check first good luck;