Answer:
The reason is because the heart requires more oxygen when exercising. Several physiological events happen to increase the blood flow and therefore oxygen flow to that muscles,including the heart.
Also the volume of blood that the heart pumps out is maintained so that the body organs receive the necessary amount of oxygen and nutrition, because if it didn't adjust the flow of blood to match activity level, you will be insufficient. Either output method will be lower than needed.
The answer is B, because carbon monoxide is a poisonous gas, it has no smell or taste and continuous inhalation may choke you to death.
Sounds like some type of B blood type honestly..
A strain is a twist, pull, and/or tear of a muscle and/or tendon. It usually results in being removed from the activity and possibly placed in the nurse's office. Hope that helped.