Which situation most directly leads to respiratory acidosis?

Identify that hypoventilation leads to increased arterial partial pressure of CO\_2, denoted as \(P\_{a}CO\_2\), which directly causes respiratory acidosis.

Contrast this with hyperventilation, which causes excessive loss of CO\_2, leading to respiratory alkalosis (not acidosis), and other conditions like loss of gastric acid or increased renal excretion of hydrogen ions, which affect metabolic acid-base balance rather than respiratory.