Which of the following accurately describes the role of introns during splicing?

Introns play a critical role in the process of splicing, which is a fundamental step in the maturation of precursor mRNA (pre-mRNA) into functional messenger RNA (mRNA) in eukaryotic cells. During splicing, introns, which are non-coding regions of a gene, are precisely excised from the pre-mRNA transcript. This removal is carried out by a complex called the spliceosome, which recognizes specific sequence motifs at the boundaries of introns and exons (the coding regions).

Once the introns are removed, the remaining exons are joined together to create a continuous sequence that will ultimately be translated into a protein. The removal of introns is essential because it allows for the correct coding sequence to be presented in the final mRNA, ensuring that the protein synthesized accurately reflects the intended genetic information. This process contributes to the regulation of gene expression and can also lead to the production of different protein variants through alternative splicing.

The other options suggest roles for introns that do not align with their biological function in splicing. For instance, introns are not retained in the final RNA transcript, nor do they determine gene expression levels or form part of the translated protein. Their primary role is indeed