What is the relative pressure in the lungs during inspiration?

A member of the 'Blues' gang was rushed into an emergency room after receiving a knife wound in the left side of his thorax. The diagnosis was pneumothorax and a collapsed lung. Explain exactly

Why the lung collapsed?

Why only one lung (not both) collapsed?

Describe the functional relationships between volume changes and gas flow into and out of the lungs.

When the inspiratory muscles contract:

a. The size of the thoracic cavity increases in diameter

b. The size of the thoracic cavity increases in length

c. The volume of the thoracic cavity decreases

d. The size of the thoracic cavity increases in both length and diameter