In the given options identify purines and pyrimidines and choose the correct option

I. Adenine                            II. Guanine            III. Cytosine                       IV. Uracil

V. Phosphate                       VI. Sugar                 VII. Thymine Pyrimidines Purines

Purines are nine membered dicyclic or double ring nitrogen bases where the two  rings are joined at 4 & 5 positions. Nitrogen occurs at 1.3,7 and 9 . purines are of two types they are adenine and guanine. Pyramidines are 6-membred, monocyclic or single ring nitrogen bases. They have nitrogen at 1 and 3 positions. Pyramidines are of three types Cytosine, Thymine and Uracil.