Solid sodium hydroxide (NaOH) is added to a beaker containing distilled water. Which statement below BEST describes the changes that occur after the addition of NaOH?
A. The hydroxyl ion concentration decreases and the pH increases.
B. The hydroxyl ion concentration increases and the pH decreases.
C. The hydronium ion concentration decreases and the pH increases.
D. The hydronium ion concentration increases and the pH decreases.