Please Read the Following Scenario to Answer the Following Questions

Multiple Choice

Please read the following scenario to answer the following questions.
While working with cultured mouse cells,a researcher unknowingly treated the cells with a mutagen that causes the deletion or insertion of individual nucleotides in DNA.Subsequently,the researcher isolated and cultured a single cell from this group and noticed that the progeny of this cell were not producing a certain protein and that this affected their survival.
-The mutation would be most harmful to the cells if it resulted in ________.

A) a single nucleotide insertion near the start of the coding sequence
B) a single nucleotide deletion near the end of the coding sequence
C) a single nucleotide in the middle of an intron
D) deletion of a triplet near the middle of the gene