nitrogenous bases in nucleic acids are classified into two distinct categories: Purines and Pyrimidines . The purines include Adenine (A) and Guanine (G), while the pyrimidines consist of Cytosine (C), Uracil (U), and Thymine (T) , . In the given options, Adenine is correctly identified as a purine, but Thymine is a pyrimidine, making their pairing under the category 'Purines' incorrect , . Understanding these fundamental biochemical classifications is a high-priority strategy for success, as NCERT textbooks serve as the primary source for approximately 95% of NEET Biology questions , .