One Common Biological Buffer Is the Carbonic Acid (H₂CO₃)

One common biological buffer is the carbonic acid (H₂CO₃) / bicarbonate (HCO₃^-) buffer. Which of the following statements describes what happens when a small amount of a strong acid is added to the buffer system:

A) the amount of bicarbonate increases
B) the amount of bicarbonate decreases
C) the amount of carbonic acid increases
D) the amount of carbonic acid decreases
E) Both b & c.