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Answer:
Sickle cell anemia is caused by a mutation in the gene that tells your body to make the iron-rich compound that makes blood red and enables red blood cells to carry oxygen from your lungs throughout your body (hemoglobin).
Explanation:
Just searched it up online. :D
The answer is A I got this answer right before
When you run it makes your heart pump blood faster ,when your pulse is up it means you veins are flowing blood and your blood has good circulation
