Final answer:
Restrictive airway diseases decrease lung compliance, leading to a reduction in the amount of air that can be forcibly exhaled from the lungs and trapping air during exhalation.
Step-by-step explanation:
Restrictive airway diseases, such as respiratory distress syndrome and pulmonary fibrosis, decrease lung compliance because the tissues become stiff and cannot bend and move properly. This decreased compliance leads to air being trapped in the lungs after exhalation, reducing the Forced Vital Capacity (FVC) and making exhalation more prolonged and difficult. Therefore, the correct answer is (a) Decrease lung compliance.
When comparing restrictive diseases to obstructive diseases like emphysema or asthma, it's important to note that in obstructive diseases, airway resistance increases due to obstructions from inflammation, fluid accumulation, or damage to the airway walls, which results in large volumes of air being trapped in the lungs after exhalation.