Of the Following Solutions, Which Has the Greatest Buffering Capacity

Of the following solutions, which has the greatest buffering capacity?

A) 0.543 M NH₃ and 0.555 M NH₄Cl
B) 0.087 M NH₃ and 0.088 M NH₄Cl
C) 0.234 M NH₃ and 0.100 M NH₄Cl
D) 0.100 M NH₃ and 0.455 M NH₄Cl
E) They are all buffer solutions and would all have the same capacity.