<prompt> A nucleic acid was analyzed and found to contain 32 adenine, 18 guanine, 17 cytosine and 33 thymine. The nucleic acid must be -Single-stranded RNASingle-stranded DNADouble-stranded RNADouble stranded DNA  <response>: According to Chargaffs rules, in any sample of double-stranded DNAThe amount of adenine equals the amount of thymineThe amount of guanine equals the amount of cytosine.The total amount of purines i.e. adenine and guanine equals the total amount of pyrimidines i.e. cytosine thymineIn the given question purines adenine 32 guanine 18 are equal to pyrimidines thymine 33 cytosine 17. Adenine 32 is equal to thymine 33 and guanine 18 is equal to cytosine 17. Thus it is double-stranded DNA. 