The oxygen revolution changed earth’s environment dramatically. which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?
a. the evolution of cellular respiration, which used oxygen to harvest energy from organic molecules
b. the persistence of some animal groups in anaerobic habitats
c. the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen
d. the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria

a. the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules

Explanation:

cellular respiration was an advantage because the process produces more ATP than anaerobic respiration, this is crucial for life because finding another metabolic pathway that is more efficient totally change things. Now a days it is still the same.

answer: 20 percent

the fish culture has become a developing commercial practice in developing countries which is already prominent in developed countries of the world. the major fish protein demand is being supplemented in developing countries is   fishing to meet the needs of the growing population. therefore, in some developing nations, the percentage of animal protein from fish in the diet can be as high as 20 percent.