Explanation:
The correct answer is C: photosynthesis. Here is a detailed explanation:
Photosynthesis:
- Photosynthesis is the process by which plants and some other organisms convert sunlight, carbon dioxide, and water into glucose and oxygen.
- During photosynthesis, plants use sunlight energy to convert carbon dioxide and water into glucose, a type of sugar, and oxygen is released as a byproduct.
- The oxygen produced during photosynthesis is released into the atmosphere, contributing to the oxygen levels in the air.
Burning of fossil fuels:
- Burning of fossil fuels, such as coal, oil, and natural gas, releases carbon dioxide into the atmosphere.
- While the burning of fossil fuels does release oxygen, it is not the primary source of oxygen in the atmosphere. The carbon dioxide released during combustion contributes to the greenhouse effect and climate change.
Respiration:
- Respiration is the process by which living organisms, including humans and animals, take in oxygen and release carbon dioxide.
- While respiration does release some carbon dioxide, it is not the primary source of oxygen in the atmosphere. It is a process that helps maintain the balance of oxygen and carbon dioxide in living organisms.
Fungi:
- Fungi are organisms that obtain nutrients by decomposing organic matter.
- While fungi play a role in the carbon cycle and decomposition, they do not directly release oxygen into the atmosphere.
In summary, the main source of oxygen in the atmosphere is photosynthesis, where plants convert carbon dioxide and water into glucose and release oxygen as a byproduct. The burning of fossil fuels, respiration, and fungi do not play the same significant role in returning oxygen to the atmosphere.