This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which is seen in RNA but not seen in DNA? 
Select and explain. 
A. Adenosine, B. Guanine, C. Uracil, D. Thymine
C: Uracil
Answer: C: Uracil 
Explanation: In the Watson-Crick base pairing, adenine (A) forms a base pair with thymine (T), as does guanine (G) with cytosine (C) in DNA.In RNA, thymine is replaced by uracil (U).Alternate hydrogen bonding patterns also occur -- paicularly in RNA -- giving rise to complex and functional teiary structures.