What is a correct statement about mutation

A mutation is the random change in the nucleotide sequence or in the organization of the DNA (genotype) of a living being, which produces a variation in the characteristics of this being and that is not necessarily transmitted to the offspring. It occurs spontaneously and suddenly or by the action of mutagens. This change will be present in a small proportion of the population (variant) or organism (mutation). The genetic unit capable of mutating is the gene, the unit of hereditary information that is part of the DNA.