Answer:
A
Explanation:
Exons are what are needed in the processing mRNA hence cannot be cut out. The regions that are cut out are introns and mainly emanate from non-protein-coding region of DNA. During RNA processing the mRNA is capped at the 5’ end and three (3) adenine nucleotides are added on 3’ end of the RNA- in a process called polyadenylation –to stabilize the mRNA. This processing is carried out by enzymes such as ribozymes and spliceosomes. RNA requires to be processed before it exits the nucleus.