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

C- Alveoli are thin walled vascualr bag like structures for exchange of gases.A trachea or wind pipe is an air conducting tube through which transport of gases takes place. B -pleural memebrane is double layered which reduces friction on the lung surface.D- diaphragham is involved in the inspiration and expriation p[rocess of breathing.