Final answer:
The correct option is A. The initiator triplet in both prokaryotes and eukaryotes is AUG, which recruits the amino acid methionine. For prokaryotes, the methionine is formylated (fMet), while it remains unmodified in eukaryotes.
Step-by-step explanation:
The initiator triplet refers to the nucleotide sequence at the start codon of an mRNA strand which signals the beginning of protein synthesis. In both prokaryotes and eukaryotes, the initiator triplet is AUG. This start codon recruits the amino acid methionine in eukaryotes and a modified form called N-formylmethionine (fMet) in prokaryotes.
The initiator tRNA, which is different for prokaryotes (tRNAMet) and eukaryotes (Met-tRNAi or Met-tRNA;), is responsible for transporting the respective methionine to the ribosome for protein synthesis initiation. The correct answer to the student's question would be A. AUG; methionine since AUG is the universal start codon and methionine is the amino acid that is initially recruited by this code, regardless of the formyl modification present in prokaryotes.