No Two People Are Genetically Identical, Except for Identical Twins

Multiple Choice

No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is

A) new mutations that occurred in the preceding generation.
B) genetic drift due to the small size of the population.
C) the reshuffling of alleles in sexual reproduction.
D) geographic variation within the population.
E) environmental effects.