Do the muscles function in passive exhalation or active inhalation?

The muscles do not function in passive exhalation.

Passive exhalation is the process of air leaving the lungs without the use of any muscles. It occurs when the diaphragm and intercostal muscles relax after inhalation, causing the lungs to recoil and push air out.

Active inhalation, on the other hand, is the process of air entering the lungs through the use of muscles. It occurs when the diaphragm and intercostal muscles contract, causing the lungs to expand and draw air in.