Responsible for 50% of the earth photosynthesis which produces a significant amount of oxygen

Oxygen is essential to enabling many of the Earth’s life forms to survive -- without access to oxygen, humans can’t live for more than a few minutes. The air that enters human lungs contains about 21 percent oxygen. The process responsible for producing most of the Earth’s oxygen is known as photosynthesis. In this process, plants and certain other organisms convert sunlight into oxygen and other products.

The answer is cometm

Ithink that b is correct but just in case wait to see if someone else answers