Two Buffer Solutions of the Same PH Are Prepared

Two buffer solutions of the same pH are prepared. After adding 15 millimoles of acid to 250 mL of one solution, the pH changes by 0.02 pH unit. Adding 15 millimoles of acid to 250 mL of the second solution results in a 0.05 pH unit change. Which statement most accurately describes the differences between the two buffer solutions?

A) The first solution has a lower capacity than the second solution.
B) The first solution has a higher concentration of conjugate acid than conjugate base.
C) The second solution has a lower concentration of conjugate base that the first solution.
D) The second solution has a higher acid to conjugate base ratio than the first solution.
E) The first solution has a higher capacity than the second solution.