Answer:
B) a nonsense mutation; this is because a nonsense mutation results in the change of a regular amino acid codon into a stop codon, which ceases translation. This fits with the problem's description of the protein that causes the symptoms as too short, as translation is the process by which proteins/polypeptides are created. A missense mutation would not be the answer because it still codes for an amino acid, which would not shorten the protein. A duplication of the gene would probably just lengthen the protein or not affect its length at all.
Video: DNA: Adenine, Guanine, Cytosine, Thymine & Complementary Base Pairing. Learn the language of nucleotides as we look at the nitrogenous bases adenine, guanine, cytosine and thymine.
