Nucleotides in a row on mRNA determine a specific amino acid in the polypeptide

This statement is true. Nucleotides in the mRNA strand determine a specific amino acid, and its position, in the polypeptide.

Explanation:

Messenger RNA (mRNA) contains the information it has received from the DNA transcription, arranged in a nucleotide sequence, necessary to perform protein synthesis.

The sequence of nitrogenous bases in the mRNA can be distributed in trios of bases, called triplets or codons. Each of the codons encodes an amino acid, the beginning of the synthesis of a polypeptide or the completion of such synthesis. The order in which the nucleotides are found also determines the order or sequence of amino acids in a polypeptide.

the answer to your question is b