What percentage of Earth's oxygen is produced by marine plants?

Marine plants, particularly phytoplankton, play a crucial role in producing oxygen through the process of photosynthesis. More than half of the Earth's oxygen supply is generated by these tiny organisms in the ocean. Estimates suggest that marine photosynthetic organisms contribute approximately 50% to 80% of the oxygen in our atmosphere.

The correct answer is close to the higher end of this range, indicating that the contributions of phytoplankton and other marine plants are significant. This high percentage reflects not only the abundance of marine plants but also their efficiency in converting carbon dioxide and sunlight into oxygen. Understanding this integral role of marine flora emphasizes the importance of oceanic ecosystems for maintaining the health of our planet and supporting life on Earth.