Which of the following observations may have resulted in the hypothesis that a codon is made up of three bases?

A) A codon of 2 bases in length, from 4 different bases, would code for a maximum of 16 different amino acids; therefore, 2 are too few.
B) A codon of 3 bases in length, from 4 different bases, would code for a maximum of 12 different amino acids; therefore 3 are too few.
C) A codon of 4 bases in length, from 4 different bases, could code for a maximum of 24 different amino acids; therefore, 4 is likely.
D) A codon of 3 bases in length, from 4 different bases, would code for a maximum of 64 different amino acids; therefore, 3 is possible.