Which of the following is a buffer solution

Choose the most correct answer: 

iii. Which of the following is a buffer solution ?
a. CH3COONa + NaCl in water
b. CH3COOH + HCl in water
c. CH3COOH+CH3COONa in water
d. HCl + NH4Cl in water

Solution:-

CH3COOH+CH3COONa in water

Chapter 3 Ionic Equilibira – Exercises (page 61)