Zoology Breathing and Exchange of Gases questions from NEET UG 2011.
A large proportion of oxygen is left unsused in the human blood even after its uptake by the body tissues. This $\mathrm{O}_2$
The figure given below shows a small part of human lung where exchange of gas takes place. In which one of the options given below, the one part A, B C or D is correctly identified along with its function. 