To order the events chronologically, we should follow the general timeline of the Earth's atmosphere and the emergence of life:
- Photosynthesizing bacteria release oxygen into the sea. (This marks the beginning of oxygen production on Earth.)
- Oxygen concentrations increase in the atmosphere. (Following the release of oxygen from photosynthetic organisms, atmospheric oxygen levels began to rise.)
- Single-celled organisms increase atmospheric methane concentrations. (This likely occurred as a result of certain microbial processes in environments where methanogens were present.)
- Many new animal species evolve. (Once oxygen levels rose sufficiently, it allowed for the development and evolution of more complex life forms.)
Based on this timeline, the correct chronological order is:
"Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere. Single-celled organisms increase atmospheric methane concentrations. Many new animal species evolve."
Thus, this order matches the first response option provided:
"Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere. Many new animal species evolve. Single-celled organisms increase atmospheric methane concentrations."
So, select that option.