The correct answer is Integumentary system.
The integumentary system includes skin and all its appendages (hair, scales, feathers, hooves, and nails) with the function to protect the body. It protects body from damage, from loss of water, from abrasion from outside and even protects the deeper tissues. On the other hand, integumentary system excretes wastes, regulates temperature, provides synthesis of vitamin D and many other things.
The answers A. C. D. are all physical reactions
The answer is B. Digestion of food
When food is digested it is chemically broken down
Hope this help!
