A solution contains a weak acid (HA) and its conjugate base (A^-) which are in equilibrium according to the following reaction:

HA (aq) <=> H⁺ (aq) + A^- (aq)

The solution has a pH of 4.75. During an experiment, a strong base (NaOH) is added gradually to this buffer solution. As the strong base is added, it reacts with the weak acid (HA) to produce water and the conjugate base (A^-). Assuming the pKa of the weak acid is 4.75, which statement best describes the behavior of the buffer solution upon the addition of NaOH?