Which from following nitrogen bases either of purine or pyrimidine does NOT contain - NH ₂ group attached with its ring?

Step-by-step solution

The nitrogenous base thymine is characterized by a pyrimidine ring with a methyl group at position 5 and two carbonyl groups at positions 2 and 4, but lacks an NH ₂ group. In contrast, adenine and guanine (purines) and cytosine (a pyrimidine) all contain amino groups at positions 6, 2, and 4, respectively. Therefore, the base lacking an NH ₂ group is thymine. The final answer is C .