Which one of the following is not a buffer solution [AIIMS 2003]

• A.                 \[0.8\,M\,{{H}_{2}}S+0.8\,M\,KHS\]
• B.                 \[2\,M\,{{C}_{6}}{{H}_{5}}N{{H}_{2}}+2M\,{{C}_{6}}{{H}_{5}}\overset{+}{\mathop{N}}\,{{H}_{3}}\,Br\]
• C.                 \[3\,M\,{{H}_{2}}C{{O}_{3}}+3\,M\,KHC{{O}_{3}}\]
• D.                 \[0.05\,M\,KCl{{O}_{4}}+0.05\,M\,HCl{{O}_{4}}\]