The answer is photosynthesis.
<span>Photosynthesis
occurs in the leaves of green plants. During photosynthesis, carbon
dioxide and water are converted into using the energy of
sunlight to glucose and oxygen. After great evolution of plants, the photosynthetic rate was increased. More plants mean more oxygen produced in the process of photosynthesis. Thus, photosynthesis </span><span> is most responsible for the increase in early Earth’s atmospheric oxygen levels.</span>
A focus group is an interview conducted by a trained moderator among a small group of respondents in an unstructured and natural manner.