( A ) 100 mL of 0.1 M HCl + 200 mL of 0.1 M $NH_4OH$
( B ) 50 mL of 0.1 M NaOH + 25 mL of 0.1 M $CH_3COOH$
( D ) 100 mL of 0.1 M $CH_3COOH$ + 100 mL of 0.1M NaOH