A solution is prepared by dissolving 0.23 mol of hydrofluoric acid (Ka = 6.8x10^-4) and 0.27 mol of sodium fluoride in water to yield 1.00 L of solution. What is the pH after the addition of 0.05 mol of HCl (Assume that the volume does not change)? A) 3.23 B) 3.11 C) 3.27 D) 3.06