In the context of aging, which of the following is an expected physiological change in the respiratory system?

A. Enhanced respiratory muscle strength: Aging is characterized by sarcopenia, which involves the progressive atrophy of the diaphragm and intercostal muscles. This leads to a reduction in maximal inspiratory and expiratory pressures, making ventilation less efficient. Muscle strength typically declines rather than improves with advanced age. B. Decreased vital capacity: As the thoracic cage becomes more rigid due to calcification of costal cartilages, the ability to fully expand the lungs diminishes. This structural change, combined with weakened musculature, reduces the maximum volume of air a person can exhale after a maximum inhalation. This is a standard finding in geriatric respiratory physiology. C. Increased alveolar surface area: Senescence involves the breakdown of alveolar septa, resulting in fewer but larger air sacs, a process often termed senile emphysema. This reduces the total surface area available for gas exchange across the alveolar-capillary membrane. It impairs the efficiency of oxygen diffusion into the bloodstream. D. Increased lung elasticity: Aging causes a loss of elastic recoil in the lung parenchyma due to changes in collagen and elastin fiber cross-linking. This loss of elasticity leads to early airway closure and increased residual volume. The lungs become more compliant but less able to recoil during expiration.