Identify the Reaction Where a Weak Acid Buffers a Base $\rightarrow$

Identify the reaction where a weak acid buffers a base.

A) OH⁻ + H₂PO₄ $\rightarrow$ H₂O + HPO₄²⁻
B) H⁺ + HPO₄²⁻ $\rightarrow$ H₂PO₄⁻
C) H⁺ + HCO₃⁻ $\rightarrow$ H₂CO₃
D) H₂CO₃ $\rightarrow$ H⁺ + HCO₃^-
E) R-NH₂ + H⁺ $\rightarrow$ R-NH₃⁺