A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This O2

Options

(a) acts as a reserve during muscular exercise
(b) raise the ₚCO₂ of blood to 75 mm of Hg.
(c) is enough to keep oxyhaemoclobin saturation at 96%
(d) helps in releasing more O₂ to the epithelial tissues.

Correct Answer:

acts as a reserve during muscular exercise

Explanation:

A 75% of oxygen is left unused in the human blood even after its uptake (25%) by the body tissues. This O₂ acts as a reserve during muscular exercise.