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Our body has developed a complex respiratory system which can meet the demand of oxygen as per requirement, but it also has a drawback. Choose that drawback from the given options.

A)  Through the respiration system pathogens also may enter into our body

B)  Rate of respiration cannot increase of decrease as per the requirement

C)  It cannot filter the oxygen from air

D)  It has any defense system to counter the pathogens

E)  None of these