First carbon of pentose sugar of nucleic acid joins
Pentose sugar present in DNAs is deoxyribose and in RNAs it is ribose. A pentose sugar (ribose or deoxyribose) is linked to a nitrogenous base (purine or pyrimidine) covalent N-glycosidic bond to form nucleoside. This linkage joins the Carbon-I of pentose sugar with nitrogen-9 of the purine base or nitrogen-I of pyrimidine base.
N-9 of pyrimidine
N-1of pyrimidine
N-1 of purine
None of the above