25.Which of the following statements BEST explains how increased CO₂ production contributes to the regulation of breathing rate? (A) Increased CO₂ directly binds to hemoglobin, preventing oxygen transport and mechanically stimulating lung expansion to increase ventilation. (B) CO2 dissolves in plasma and is rapidly exhaled without chemical conversion, and breathing rate increases in response to decreased blood O2 levels. (C) Increased CO₂ is converted to carbonic acid by carbonic anhydrase in red blood cells. Carbonic acid dissociates leading to an increase in H+ concentration and a decrease in pH, which is detected by chemoreceptors. (D) CO2 produced during exercise remains primarily in gaseous form within tissues, directly activating stretch receptors in the lungs to increase breathing frequency. (E) Elevated CO2 suppresses respiratory center activity by stabilizing blood pH, thereby reducing the need for increased ventilation during exercise.