Which of the following is correct about the polyadenylation mechanism?
A:a long chain of adenine nucleotides is added to the 3' end of mRNA during terminationof transcription
B:a long chain of uracil nucleotides is added to the 3' end of mRNA during terminationof translation
C:a long chain of guanine nucleotides is added to the 3' end of mRNA during termination of translation