A 500-ML Sample of a 0

Multiple Choice

A 50.0-mL sample of a 0.100 M solution of a weak acid HA has an equilibrium pH of 4.00. After 1.0 × 10^-3mol of a substance X is added to the solution, it is observed that the pH of the solution increases. What might be true about substance X? I. X might be a strong base that partially neutralized some weak acid.
II) X might be a strong acid that made the solution more acidic.
III) X might be a soluble ionic compound containing the anion A^-.

A) I only
B) II only
C) III only
D) I or III
E) II or III