According to the 'Role of CO2 in Earth's Atmosphere' assignment, Earth is considered a 'closed system' because *

bc blah

explanation:

bc blah

maybe because its impossible for balloons to lift a whole entire house.

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.