Solution

A codon is a trinucleotide sequence of DNA or RNA that corresponds to a specific amino acid. UGA, UAA, and UAG are stop codons. AUG is the codon for methionine, and is also the start codon. The stop codon are also known as nonsense codons or termination codons as they do not code for an amino acid. The three stop codons have been named as amber (UAG), opal or umber (UGA) and ochre (UAA). The codon AUG is called the start codon as it the first codon in the transcribed mRNA that undergoes translation. AUG is the most common start codon and it codes for the amino acid methionine (Met) in eukaryotes and formyl methionine (fMet) in prokaryotes.
So, the correct option is 'D'.