In physiological terms, a set point can be defined as

A) the value of a parameter, such as the concentration of sugar in the blood, that homeostatic mechanisms aim to maintain.
B) the value of a parameter, such as the concentration of sugar in the blood, that set homeostatic mechanisms in motion.
C) the location in a thermal gradient at which a poikilothermic organism rests, reflecting is preferred body temperature.
D) the winning stroke in a tennis match.