If a Few Drops of HCl Is Added to the Buffer

Multiple Choice

If a few drops of HCl is added to the buffer solution with the following equilibrium, ________.
NH4+(aq) + H₂O(1) ⇔ H3O+(aq) + NH3(aq)

A) the concentrations of both NH3 and NH4+ decrease
B) the concentrations of both NH3 and NH4+ increase
C) the concentration of NH3 increases but NH4+ decreases
D) the concentration of NH3 decreases but NH4+ increases