Answer:
Three main body systems are at work.
Step-by-step explanation:
Essential body systems are at work such as the nervous, digestive, and respiratory systems. Note that from the moment you start going home from school your Respiratory system starts working, allowing you to breathe as you enter the house.
Furthermore, your Nervous system allows you to smell cookies baking in the kitchen. Finally, your Digestive system starts working as you eat the cookie and drink the milk.