A buffering solution is made from acetic acid (CH3CO2H) and its conjugate base (CH3CO2–). Which reaction describes the buffering effect of the solution when an acid is added to the solution? a. CH3CO2H(aq) + OH(aq) → CH3CO2–(aq) + H2O(l) b. CH3CO2–(aq) + H2O(l) → CH3CO2H(aq) + OH(aq) c. CH3CO2H(aq) → CH3CO2–(aq) + H+(aq) d. CH3CO2–(aq) + H+(aq) → CH3CO2H(aq)