Final answer:
A gene is a specific segment of DNA on a chromosome that carries the code for making a particular protein or polypeptide chain.
Step-by-step explanation:
The best definition of a gene is c. A specific segment of DNA on a chromosome. Genes serve as the instructions for making specific polypeptides or proteins, which are essential for the myriad functions within an organism. A gene consists of a sequence of nucleotides in the DNA that not only carries the code for making a specific polypeptide chain but also plays a vital role in hereditary processes. Interestingly, the genetic code is interpreted through a series of three-letter codes, which represent the different amino acids used to build proteins.