Botonomy is the study of plants
Answer:
it would be C, or the third one. The percentage of red blood cells in a sample of human blood is normally about 45%.
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<span>When the diaphragm contracts and moves lower, the chest cavity enlarges, reducing the pressure inside the lungs. To equalize the pressure, air enters the lungs. When the diaphragm relaxes and moves back up, the elasticity of the lungs and chest wall pushes air out of the <span>lungs. hope this helps</span></span>