This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
Which of the following is not a pyrimidine? 
Select and explain. 
A. Ubracil, B. Thymine, C. Adenine, D. Cytosine
C: Adenine
Answer: C: Adenine 
Explanation: Adenine is a purine and not a pyrimidine Ref-Sathyanarayana 4/e