Which of the following mixtures can be regarded as buffer ?

Options

A. 500 ml 0.2 (M) `CH_(3)COOH + 1000 ml 0.2 (M) NaOH `
B. 500 ml 0.2 (M) `CH_(3)COOH + 300 ml 0.2 (M) NaOH`
C. 500 ml 0.2 (M) `CH_(3)COOH + 500 ml 0.2 (M) NaOH`
D. 500 ml `0.2 (M) CH_(3)COOH +500 ml 0.2 (M) NH_(4)OH`