Which of the following is an example of a mutation?

A change in nucleotide sequence is the definition of a mutation. Mutations can occur in various forms, such as substitutions, insertions, or deletions of nucleotides in the DNA. These changes can affect the way genes function, potentially altering the traits or characteristics of an organism. Mutations can lead to variations within a population, which are essential for the process of evolution.

Uniform chromosome structure refers to a consistent arrangement across chromosomes and does not indicate any changes or alterations in the genetic material, thus it does not represent a mutation. A lethal genetic condition results from specific mutations but is not a mutation itself; it is the outcome of such changes. A stable haploid state refers to the condition of having one complete set of chromosomes and does not imply any genetic changes or mutations.