When the inspiratory muscles contract,

A) thoracic volume increases.
B) pleural pressure increases.
C) the alveolar pressure increases.
D) expiration occurs.
E) thoracic volume decreases.

Inspiratory Muscles

Muscles involved in inhalation, primarily the diaphragm and intercostal muscles, which expand the thoracic cavity.

Pleural Pressure

The pressure within the pleural cavity, which can influence lung expansion and contraction.

Alveolar Pressure

The pressure within the alveoli of the lungs, which influences breathing and gas exchange.