Build up of calcium in your blood which can cause nausea and vomiting,weakness etc.
I think because so they can stay healthy for while
Cardio I'm sure, ( they want me to type more so this is why I'm writing this )
Answer:
they affect the brain by slowing it down and making it stunt the 'growth' of knowledge
Explanation:
although, they do be cool
I think C because if something happens you might drown and no one to help you. but that's just a guess