B

A low arterial pH (acidemia) together with a low pCO₂ indicates that the primary disturbance is metabolic (acid being added or bicarbonate lost), while the fall in pCO₂ reflects the expected respiratory compensation by hyperventilation. This pattern is characteristic of metabolic acidosis rather than a primary respiratory disorder [Quintanilla, 1976, PMID 981088; Daniel, 2004, PMID 15580022].