Biology question?

Which is true of the human respiratory system A. gas exchange occurs all along the respiratory system B. the nasal passages clean the air traveling to the lungs C. White blood cells carry most of the oxygen that is carried in the blood D. the mouth is the opening to the respiratory system E. none of these are true... show more Which is true of the human respiratory system
A. gas exchange occurs all along the respiratory system
B. the nasal passages clean the air traveling to the lungs
C. White blood cells carry most of the oxygen that is carried in the blood
D. the mouth is the opening to the respiratory system
E. none of these are true of the respiratory system
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