An anticodon is the sequence of the nitrogenous bases on the:

Explanation

The correct answer is Option D. An anticodon is a sequence of three nucleotides on a tRNA molecule that recognizes and pairs with a complementary codon on an mRNA molecule. This pairing is crucial for the translation process, ensuring that the correct amino acid is added to the growing polypeptide chain. Option A is incorrect because DNA does not contain anticodons. Option B is incorrect as anticodons are not found on mRNA. Option C is misleading because while tRNA is where the amino acid is attached, the anticodon itself is responsible for recognizing codons on mRNA, not for amino acid attachment. Option E is incorrect because the mRNA's start codon, not the anticodon, initiates protein synthesis.