Which of the definitions below best defines a mutation?

A. A change in a cell's genetic material

b. The infectious agent that causes disease

c. A substance that increases in concentration with trophic level

d. The influence of human beings on nature

The correct answer is: A. A change in a cell's genetic material.

Mutations occur in DNA as a result of mistakes during the DNA replication (when repair mechanisms don't fix it) or as the result of environmental factors (e. g. UV light). Mutations can have positive impact, by increasing the genetic variation or can have negative effect, causing the diseases or cancer.