Answer:maintaining homeostasis
Step-by-step explanation:
The process of maintenance of relatively constant internal i environment of an organism is called homeostasis.
Therefore the sudden change in the body temperature of the duck in water is adjusted by the deep con striction of the capillaries which retained heat to the internal body structures, and reducing convention to upper body surface , to maintain constant bidy temperature in respective of the change in the external temperature.
This is homeostasis.