 
 <translate> To answer the above question, the relevant sentence is: Nucleotides are the building blocks of nucleic acids; they are composed of three subunit molecules: a nitrogenous base, a five-carbon sugar (ribose or deoxyribose), and at least one phosphate group.
So, the final answer is a nitrogenous base. <hau> Don amsa tambayar da ke sama, jumlar da ta dace ita ce: Nucleotides sune ginshiƙan ginin nucleic acid; sun ƙunshi kwayoyin subunit uku: tushe na nitrogen, sukari mai carbon biyar (ribose ko deoxyribose), kuma aƙalla ƙungiyar phosphate ɗaya. Saboda haka, amsar karshe ita ce tushe na nitrogen. 