A student titrates 50.0 mL of a 0.10 M aqueous solution with 0.10 M titrant at 25 °C. The titration curve begins at pH ≈ 11 and has an equivalence point at pH ≈ 5.8. Which combination of reactant and titrant most plausibly produced this curve?
a) CH3COOH titrated with NaOH
b) NaOH titrated with CH3COOH
c) Aqueous NH3 titrated with HCl
d) HCl titrated with NaOH