Why Would a Collapsed Right Lung,due to a Pneumothorax,also Collapse

Why would a collapsed right lung,due to a pneumothorax,also collapse the left lung?

A) The mediastinum is a mobile rather than a rigid partition between the two pleural sacs, thereby allowing the increased pressure in the side of the chest that is open to push the heart and other mediastinal structures toward the intact side, where they can exert pressure on the left lung.
B) Subatmospheric pressure increases from its normal level and thereby moves from high pressure area (right lung) to low pressure area (left lung) .
C) When intrathoracic pressure increases, the mediastinum softens and thereby allows the increased pressure in the side of the chest that is open to push the heart and mediastinal structures toward the intact side, where they can exert pressure on the left lung.
D) Intrathoracic pressure increases from its subatmospheric level to an atmospheric level, thereby allowing the pressure within the chest to increase in proportion to the volume of the thorax.