Answer : As per the definition of the buffer solution "<em>It</em><span><em> is an aqueous </em></span><em>solution</em><span><em> consisting of a mixture of a weak acid and its conjugate base, or vice versa".
</em>so considering the above given condition for </span>
and 
act as buffer because it satisfies and qualifies the conditions of behaving as a buffer when mixed in equal amounts,
whereas HCl and NaOH are strong acid and strong base which does not satisfies the criteria for being called as buffer.
As buffer needs a weak acid and its conjugate base to behave and act as buffer and resist any pH change.
</em>so considering the above given condition for </span>
whereas HCl and NaOH are strong acid and strong base which does not satisfies the criteria for being called as buffer.
As buffer needs a weak acid and its conjugate base to behave and act as buffer and resist any pH change.