Answer:
The answer is letter a, chemical evolution.
Step-by-step explanation:
Chemical Evolution is one of the processes that helps explain the origin of life. It states that the first living cell on earth started from non-living matters that were not capable of reproducing.
This non-living matter could be both organic and inorganic molecules. It is said that the structures of these molecules changed over time (example is protein breaking down when exposed to too much heat). When these systems become complex, they form new structures (this is known as repetitive reproduction). This then gives rise to bacteria.
Thus, this explains the answer.