question_answer

A large proportion of oxygen is left unused in the human blood even after its uptakes by the body tissues. This \[{{O}_{2}}:\]

A)  helps in releasing more\[{{O}_{2}}\]to the epithelial tissues

B)  acts as a reserve during muscular exercise

C)  raises the\[pC{{O}_{2}}\]of blood to 75 mm of Hg

D)  is enough to keep oxyhaemoglobin saturation at 96%