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

Question

https://clay6.com/mpaimg/494_a.jpg

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