Q.
A. External intercostal muscles, radial muscles contract and volume of the thoracic cavity de creases during inspiration
B. External intercostal muscles, radial muscles relax and volume of the thoracic cavity decreases during expiration
C. Radial and intercostal muscles contract and pressure in the thoracic cavity decreases during expiration
D. Radial muscles and external intercostal muscles contract and size of the thoracic cavity increases during inspiration
E. None of the above
Correct choice: B
Explanation: