One of the Buffers That Contribute to PH Stability in Human

One of the buffers that contribute to pH stability in human blood is carbonic acid (H₂CO₃) . Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO₃⁻) and a hydrogen ion (H⁺) . Thus,
H₂CO₃ ↔ HCO₃⁻ + H⁺
If the pH of the blood drops, one would expect

A) a decrease in the concentration of H₂CO₃ and an increase in the concentration of HCO₃⁻.
B) the concentration of hydroxide ion (OH⁻) to increase.
C) the concentration of bicarbonate ion (HCO₃⁻) to increase.
D) the HCO₃⁻ to act as a base and remove excess H⁺ with the formation of H₂CO₃.
E) the HCO₃⁻ to act as an acid and remove excess H⁺ with the formation of H₂CO₃.