Assertion (A): Thoracic chamber is anatomically an air-tight chamber and any change in its volume has no effect whatsoever on the pulmonary cavity.
Reason (R): Lungs are situated in the thoracic cavity and this arrangement is essential for breathing.
With respect to the above mentioned statements, choose the correct answer from the following options.
1. (A) and (R) are true and (R) is the correct explanation of A
2. (A) and (R) are true but (R) is not the correct explanation of A
3. (A) is true but (R) is false
4. (A) is false but (R) is true