Which of the Following Has the Highest Buffer Capacity

Multiple Choice

Which of the following has the highest buffer capacity?

A) 0.10 M H ₂PO ₄ ⁻/0.10 M HPO ₄ ²⁻
B) 0.50 M H ₂PO ₄ ⁻/0.10 M HPO ₄ ²⁻
C) 0.10 M H ₂PO ₄ ⁻/0.50 M HPO ₄ ²⁻
D) 0.50 M H ₂PO ₄ ⁻/0.50 M HPO ₄ ²⁻
E) They all have the same buffer capacity.