Which change is an example of maintaining dynamic equilibrium

A change in body temperature is an example of dynamic equilibrium where balance is attained within an environment as the consequence of internal control mechanism that continuously contrast outside forces that tend to change that environment. The human body produces heat as a by product of metabolic processes and uses behavioral and physiological mechanisms to control the rate at which heat is lost through skin when in a cold environment.

with pass cost = $25

without pass cost = 3x number of days going the the class