B. Soil Contamination
All the other answers are talking about clean and pure things while this answer is the only negative one. So B is your answer.
I believe it's the theory that cells are the building blocks of life and without cells, there would be no life at all. Its also stated cells come from pre-existing cells and each organism has either one or more.
During respiration, members of the animal kingdom use oxygen and then release carbon dioxide as a waste gas.
Members of the animal kingdom have a respiratory system that is composed of muscles, and airways that functions together to transport air into lungs, and the oxygen is used by cells. Carbon dioxide is also transported away from the cells as a waste gas. Respiration relies on other systems, such as the circulatory system, to transport oxygen and carbon dioxide to and from cells.
