Which Solution Has the Greatest Buffering Capacity

Multiple Choice

Which solution has the greatest buffering capacity?

A) 0.335 M NH₃ and 0.100 M NH₄Cl
B) 0.085 M NH₃ and 0.090 M NH₄Cl
C) 0.540 M NH₃ and 0.550 M NH₄Cl
D) 0.200 M NH₃ and 0.565 M NH₄Cl
E) They are all buffer solutions and would all have the same capacity.