The correct option is D Both assertion and reason are false
Most of the amino acids in the genetic code are encoded by at least two codons. In fact, methionine and tryptophan are the only amino acids specified by a single codon. However, the reverse is not true. One codon does not code for more than one amino acid.
A codon being degenerate means that a single amino acid may be coded for by more than one codon.
A codon is not ambiguous - one codon does not code for more than one amino acid. For instance, codons GAA and GAG both specify glutamic acid and exhibit redundancy; but, neither specifies any other amino acid and thus are not ambiguous.