Final answer:
The correct answer to the student's question is B. A gene, which is a segment of DNA responsible for encoding the information to create a specific functional RNA or protein.
Step-by-step explanation:
A gene is a sequence of DNA that contains the information required for making a particular functional RNA or protein. The genetic information necessary to build a protein through gene expression, which is the active interpretation of the information coded in a gene, results in the production of a functional gene product. While the genome is the entire complement of an organism's DNA found within virtually every cell, a gene is the physical and functional unit of heredity that codes for a specific peptide or RNA molecule.
The correct answer to the question is B. A gene. Each gene provides the code for a single polypeptide chain or an RNA molecule which plays a significant role in the cell's functions. These genes are organized into segments along the chromosomes, being part of the organism's overall genome.