Answer: Homeostasis
Explanation: Homeostasis is the tendency of an organism to maintain stable internal conditions amid environmental change.
Cells in the body need certain conditions in order to function properly. Homeostatsis maintains those conditions even when the external environment is changing. For example, cells need to have enough oxygen to produce the right amount of energy. When people exercise, their cells need more energy. The body is able to increase respiration and circulation so that the cells can still get the oxygen that they need. Increased circulation simultaneously helps the body dissipate the extra heat that is created.
Reproduction is the process through which a species produces offspring.
Commensalism is the relationship between two organisms in which one benefits and the other neither benefits nor is harmed.
Metabolism refers to the physical and chemical changes in an organism which release or use energy.
