Final answer:
When thoracic wall compliance is decreased, the intrapleural pressure does not decrease normally during inhalation, which affects the amount of air that enters the lungs.
Step-by-step explanation:
If the compliance of the thoracic wall is decreased, A) the intrapleural pressure would not decrease normally during inhalation. Compliance refers to the ability of the thoracic wall to stretch and expand under pressure, which is critical for proper breathing. During inhalation, the thoracic cavity expands, causing a decrease in intrapleural pressure, which then allows air to flow into the lungs due to the pressure gradient. However, if the thoracic wall is less compliant, this expansion is hindered, making it difficult to create the necessary drop in intrapleural pressure. Consequently, less air is drawn into the lungs during the process of inhalation.