A.increase current global forest cover by 10 percent.
Explanation:
Plants are the natural source of oxygen as they release oxygen as by-product during the process of photosynthesis. Deforestation is one of the major cause of reduced oxygen level in current atmosphere. Reforestation and afforestation are cost effective process that could increase the oxygen level of air. Therefore, an increase current global forest cover by 10 percent is most effective way to increase the oxygen content of air.
"Increase current global forest cover by 10 percent" is the one among the following choices given in the question that is the most <span>effective way to increase the oxygen content of air. he correct option among all the options that are given in the question is the first option or option "A". I hope it helped you.</span>
