In the aging respiratory system, the rib cage becomes

• A. Rigid
• B. Flexible
• C. Expandable
• D. Fragile

Answer: (A)

As people age, the chest wall becomes less compliant, so the rib cage tends to become rigid. This happens because costal cartilages often calcify and joints in the thoracic cage stiffen, and spinal and muscular changes reduce overall flexibility. With a stiffer rib cage, the chest cannot expand and recoil as easily during breathing, leading to shallower breaths and lower chest wall expansion. This is why the best description is rigid.

Choosing other terms like flexible or expandable would imply the chest wall can move more easily, which isn’t the typical aging change. Fragile describes bone fragility from osteoporosis, which is a separate issue; the question is about the chest wall’s mechanical flexibility, which ages toward rigidity rather than increased fragility.