You Notice That a Single Change to a Gene Causes

You notice that a single change to a gene causes the sequence of protein B to become drastically shorter.What could that change be?

A) All the codons for the amino acid methionine have been changed to cysteine.
B) Two copies of the gene have been fused together.
C) The stop codon in the gene has been changed to another codon.
D) A stop codon has been inserted in the middle of the gene.
E) Several codons have been added to the end of the gene.