Which describes DNA mutation types?

• A. Inversion
• B. Translocation
• C. Deletion or substitution of a nucleobase
• D. Duplication

Answer: (C)

Mutations are changes in the DNA sequence, and at the most basic level they involve alterations to individual nucleotides. Deletion or substitution of a nucleobase fits this description because substitution replaces one base with another, potentially altering a codon, while deletion removes a base, which can shift the reading frame and change downstream amino acids. These are classic point mutations that occur directly at the nucleotide level. Inversions, translocations, and duplications describe rearrangements of larger DNA segments, which are considered chromosomal mutations rather than simple base-level mutations. So focusing on deletion or substitution of a nucleobase captures the fundamental nucleotide changes that underlie many mutations.