Answer:
D
Step-by-step explanation:
An enzyme called poly (A) polymerase (PAP) is part of the same protein complex that cleaves the pre-mRNA and it immediately adds a string of A nucleotides, called the poly (A) tail, to the 3′ end of the just-cleaved pre-mRNA. The poly (A) tail added protects the mRNA from degradation, aids in the exportation of the mature mRNA to the cytoplasm and helps in binding proteins involved in initiating translation.