Answer:
C. A dead organism
Explanation:
A body is said to be in equilibrium if there is no likelihood of a change with relation to time. This also means that there is no detectable change in such a system.
However in relation to Biology a body is said to be equilibrium when it is dead. The metabolic state of the organism is usually zero and in a state of rest. There is absence of internal and external biochemical activity. Having life in carrying out cellular activities is the main determinant in the equilibrium state of an organism.