What is the correct description of intrapleural pressure?

A.It is good for the blood flow of internal thoracic vein

B.No change in intrathoracic pressure during breathing

C.the intrathoracic pressure was greater than the pulmonary retraction force.

D.the intrathoracic pressure was negative pressure during pneumothorax

正确答案：It is good for the blood flow of internal thoracic vein