Final answer:
The same gene can code for different proteins through the process of alternative splicing, which involves removing introns from an mRNA (option a) molecule. This allows for a single gene to increase the diversity of proteins that can be synthesized.
Step-by-step explanation:
The same gene is able to code for different proteins depending on the combinations of introns removed from a messenger RNA (mRNA) molecule. The process by which this occurs is known as alternative splicing, whereby various combinations of exons are pieced together after the introns are removed. The mRNA then serves as the template for protein synthesis, carrying the genetic information from the DNA to the ribosome, where the protein is assembled.
Introns are non-coding regions that must be spliced out of the pre-mRNA, and the exons - the coding regions - are rejoined to form the mature mRNA. This splicing process allows for multiple protein variants (isoforms) to be produced from a single gene, significantly increasing the diversity of proteins that can be synthesized in eukaryotic cells.
Therefore, the correct answer to the question is a) mRNA.