The correct option is C Degenerate
Genetic code is the term we use for the way that the four bases of DNA--the A, C, G, and T --are strung together in a way that the cellular machinery, the ribosome, can read them and turn them into a protein. In the genetic code, each three nucleotides in a row count as a triplet and code for a single amino acid. The genetic code is degenerate. Some amino acids are encoded by more than one codon, in as much as there are 64 possible base triplets and only 20 amino acids. In fact, 61 of the 64 possible triplets specify particular amino acids and 3 triplets (called stop codons) designate the termination of translation.
So, the correct option is D.