Assertion (A): Alveoli contain an extensive network of blood vessels.
Reason (R): Alveoli is the site where exchange of gases occurs.
- The alveoli of lungs are richly supplied with blood
- Alveoli are the sites where exchange of gases (O 2 and CO 2 ) occurs between blood and the atmosphere.
- The alveoli increase the surface area for this exchange of gases and hence have an extensive network of blood vessels to maximise efficiency.
- The assertion is True
- The reason is True
The reason is the correct explanation of the assertion
So, the correct option is (a)