Final answer:
A single codon consists of three nucleotides, which corresponds to the genetic code for a single amino acid in a DNA or RNA molecule. There are 64 possible codons that translate into 20 common amino acids, indicating the degeneracy of the genetic code.
Step-by-step explanation:
A single codon contains three nucleotides. A codon is a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule. The sequence of nucleotides within a codon determines which amino acid will be added next during protein synthesis.
There are a total of 64 possible codons that translate into 20 common amino acids, which demonstrates the degeneracy of the genetic code, meaning multiple codons can code for the same amino acid. Beyond these, some codons serve as start or stop signals during the translation process. Thus, the correct answer to the original question is b) 3.