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 type of RNA has the highest percentage of modified base? 
Select and explain. 
A. mRNA, B. tRNA, C. rRNA, D. snRNA
B: tRNA
Answer: B: tRNA 
Explanation: The transfer RNAs show extensive internal base pairing and acquire cloverleaf-like structureThey contain significant propoion of unusual basesThese include dihydrouracil, pseudouridine, and hypoxanthineRef: DM VASUDEVAN, 7th edition, page no: 596,597