Genetic variation refers to differences among individuals in the composition of their genes or other DNA segments.

• A. Mutations that occur during replication
• B. Differences among individuals in the composition of their genes or other DNA segments
• C. A change in allele frequencies over time
• D. Environmental influences on phenotype

Answer: (B)

Genetic variation is the differences in DNA sequence among individuals. It includes differences in genes themselves as well as in noncoding DNA, reflecting the actual genetic differences you can compare between individuals. The option that describes differences among individuals in the composition of their genes or other DNA segments matches this definition exactly. Mutations during replication are a source of new variation, but they describe how variation arises rather than what variation is. A change in allele frequencies over time refers to evolution in a population, not the existence of genetic differences itself. Environmental influences on phenotype pertain to how traits appear and vary due to the environment, not to differences in the DNA sequence.