We would expect that a 15-nucleotide sequence that includes a stop codon at the end (as part of the 15-nucleotide sequence) will direct the production of a polypeptide that consists of:

four amino acids are produced from 15 nucleotide sequence which includes last three nucleotides for stop codon.

Explanation:

Every three nucleotides makes one codons that encodes one amino acid. As in this question there are only 15 nucleotides and each 3 nucleotides makes one codon hence only 4 amino acids are encoded by this sequence. Last three nucleotides for stop codon which does not encodes an amino acid.

Answer is 15 nucleotide sequence encodes 4 amino acids and one stop codon