Answer the following question given this paragraph: 

5.3 Functions of the Integumentary System The skin plays important roles in protection, sensing stimuli, thermoregulation, and vitamin D synthesis. It is the first layer of defense to prevent dehydration, infection, and injury to the rest of the body. Sweat glands in the skin allow the skin surface to cool when the body gets overheated. Thermoregulation is also accomplished by the dilation or constriction of heat-carrying blood vessels in the skin. Immune cells present among the skin layers patrol the areas to keep them free of foreign materials. Fat stores in the hypodermis aid in both thermoregulation and protection. Finally, the skin plays a role in the synthesis of vitamin D, which is necessary for our well-being but not easily available in natural foods.


Q: What system, which includes the skin, plays important roles in protection, sensing stimuli and thermoregulation?

 Choices:

- digestive system

- pectins system

- teleporters system

- integumentary system

A:
integumentary system
