A frame-shift mutation where a nucleotide is added to the genetic material

• A. Deletion mutation
• B. Substitution mutation
• C. Insertion mutation
• D. Point mutation

Answer: (C)

A frame-shift mutation happens when nucleotides are inserted or deleted, changing how the genetic code is read in groups of three (codons) from that point forward. When a single nucleotide is added, every codon downstream is read in a new way, so the amino acids produced after the mutation change dramatically. This often yields a nonfunctional protein and can introduce an early stop signal.

So, adding one nucleotide is exactly what creates a frame shift through insertion, which is why this option is the best description. In contrast, a substitution changes one base within a codon but doesn’t shift the reading frame, and a deletion can cause a frame shift only if it’s not in multiples of three. A point mutation is typically another term for a substitution and doesn’t imply a frame shift.