the figure shows a diagrammatic view of human respiratory system with labels A, B , C and D . Select the option which given correct identification and main function and / or characteristic

Options

A. A- Trachea-long tube supported by complete cartilaginous rings for conducting inspired air
B. B- Pleural membrane - surround ribs on both sides to provide cushion against rubbing
C. C-Alveoli-thin- walled vascular bag-like structure for exchange of gases
D. D-Lower end of lungs - diaphragm pulls it down during inspiration.

Answer

C

Explanation

C-Alveoli are thin -walled vascular bag-like structures for exchange of gases. A -trachea on windpipe is an air conducting tube through which trasport of gases takes place. B- pleural membrane is double layered, which reduces frication on the lung surface. D-diaphragm is involved in the inspiration and expiration process of breathing .