The Following Question Refers to the Following System: a 1 $\times$

The following question refers to the following system: A 1.0-liter solution contains 0.25 M HF and 0.83 M NaF (K_a for HF is 7.2 $\times$ 10^-4) . What is the pH of this solution?

A) 3.14
B) 3.66
C) 2.62
D) 0.52
E) 10.34