Ans. Phenylalanine.
Genetic codes or codons are triplet codes, made up of three nucleotides. Each genetic code codes for a particular amino acid during translation. There are total 64 codons, out of which 61 codes for amino acids, while 3 act as stop codons.
According to Universal Genetic Code chart, first genetic code is UUU that codes for phenylalanine amino acid.
Thus, the correct answer is option). 'phenylalanine.'