Answer:
D
Step-by-step explanation:
When you count the number of bases after the mutation in the strand, you discover an additional one base(Adenine). Addition and deletion mutations are more likely to be lethal than substitution mutations. This is because the latter mutations cause a frameshift mutation that will disrupt the codon sequences downstream of the mutation. Ultimately, this largely affects the amino acid sequence of the translated protein, its properties, and how it folds (all which relate to and affect its function).