The answer is Circulatory System. It is responsible for moving blood and oxygen around the body, etc. (Brainiest answer plz and thank you) Hope this helped!
I would be answering what happened and why
Answer:
Can not be determined.
Explanation:
Only the number of calories is given and this is not enough to find out Alex's TEE as there is no detail about his height, weight and age is given.
Please comment if you have more information and ill edit the answer!