Question

what is the percentage of oxygen produced by marine plants? 75 50 45 20

Explanation:

Marine plants (including phytoplankton) are responsible for producing about 75% of the Earth's oxygen through photosynthesis. This is a well - known fact in the field of environmental sciences and biology related to marine ecosystems.

Answer:

75 (the option corresponding to 75, assuming the options are presented as radio buttons with 75 as one of the choices for the percentage of oxygen produced by marine plants)