DNA (Deoxy Ribo NUCLEIC Acid)Thymine is PRESENT in it.Double stranded structure.RNA (Ribo Nucleic Acid)Thymine is replaced by Uracil in it.Single-stranded structure.So, correct answer is RNA as it CONTAINS only single string of nucleotide.Explanation:Nucleotide are the monomers whose repetition makes polynucleotides or nucleic acid like DNA and RNA.Nucleotide consists of three components:1) Nitrogenous basewhich is further consists of Purine and PYRIMIDINE→ Purine = Adenine, Guanine→ Pyrimidine = Cytosine, Thymine2) Pentose sugar3) Phospheric acid(All three components together make nucleotide.)In structure of DNA, Purine always make H-bond (hydrogen bond) with Pyrimidine. Always Adenine make double bond double bond with Thymine and Cytosine make triple H-bond with Guanine.Nucleoside is formed by combination of nitrogeneous base and pentose sugar.What is Nucleic Acid?→ These are the chemicals or molecules which are responsible for INHERITANCE of characters. They are present in nucleus of cell.They are mainly of two types: DNA and RNA