The correct answer is RNA processing.
Explanation: In eukaryotic cells, RNA processing occurs after transcription and is an essential step in the maturation of mRNA. During this process, introns (non-coding regions of the RNA) are removed, and exons (coding sequences) are spliced together to form the final messenger RNA (mRNA) molecule. This mature mRNA can then be translated into protein. Therefore, the removal of introns is a key aspect of RNA processing.