Propanoic acid is an organic acid. At 298 K the pH of a 50.0 mL sample of 0.20 M of it is 3.0. The pH of the solution formed by mixing 25.0 mL of 0.2 M sodium propanoate solution with 25.0 mL of 0.1 M propanoic acid will be

A

3.3

B

5.3

C

5.6

D

6.3