The digestive system's homeostatic relationship with the system is characterized by the fact that our bodies can store fat in the hypodermis.

 The INTEGUMENTARY SYSTEM  is the largest organ system of the body that consists of the skin, hair, nails, glands and nerves. It functions as a barrier to protect the body from the external environment. It also regulates body temperature which is achieved through its homeostatic relationship with the digestive system that includes the digestion and assimilation of dietary fats and oils since they can be deposited to the dermis.

Therefore, the system to which the digestive system forms a homeostatic relationship is the INTEGUMENTARY SYSTEM.

C) reflection (i also looked up the other choices just to make sure)