Task: Question Answering
Input (English): Question: Which of the following modifications is not part of the maturation process suffered by the precursors of the tRNAs? 
 Options:  <1> Modification of bases. <2> Elimination of the 5'-end leader sequence. <3> Elimination of the final segment of the 3 'end. <4> Addition of CCA to the 3 'end. <5> Polyadenylation of the 3'-end.
Output (English): 5