To build a single stranded RNA ( ribonucleic acid ) , we need for nucletotide and ribose sugar. Nucleotide is refer to as building block of DNA and RNA. They are composed of three parts: a phosphate group, a 5-carbon sugar, and a nitrogenous base. Nucleotides are helpful in enzyme reactions, metabolism etc.
For the compoustion of RNA :
1) ribose
2) Any of the nucleotide base that is Adenine , guanine , uracil , cystosine.
Please see the attched structure also .