An acidic buffer solution is prepared by mixing a weak acid and its salt with a strong base. A basic buffer solution is prepared by mixing a weak base and its salt with strong acid. A buffer solution cannot be obtained by mixing a strong acid with a strong base.\\\\(HCl\\\\) is a strong acid and \\\\(NaOH\\\\) is a strong base, therefore it forms salt and not a buffer solution.\\\\(NH_4OH\\\\) and \\\\(CH_3COOH\\\\) is a mixture of a weak acid and weak base, therefore it forms salt and not buffer solution. Hence option C & D is correct.