Answer:
Closed the first one
Explanation:
In amphibians, reptiles, birds, and mammals, blood flow is directed in two circuits: one through the lungs and back to the heart, which is called pulmonary circulation, and the other throughout the rest of the body and its organs including the brain (systemic circulation).
most mammals, have closed cardiovascular systems. The two main circulation pathways in invertebrates are the single and double circulation pathways.
A) taking in extra water can result in cramps so it is not A
B)you should do warm up,So that the body would be ready to handle the sudden increase in body speed,So it is not B
C)working through any pain,is good at some reason but not on all the experience so its not C
D)you need to plan on taking proteins,Proteins helps in strengthening in bones and helps in the supply of oxygen to the cells(for eg tennis players eat a banana before,middle and after the game or gym workers take protein bars to work out more)
