Which process results in the genetic variation observed in offspring?

The process that leads to genetic variation in offspring is meiosis. This specialized form of cell division occurs in sexually reproducing organisms and is crucial for the formation of gametes—sperm and egg cells. During meiosis, homologous chromosomes undergo a series of events including recombination (crossing over) and independent assortment, which shuffle genetic material between the chromosomes. This results in each gamete carrying a unique combination of genes. When fertilization occurs, the genetic variation is further amplified as two gametes combine to form a new individual, carrying genes from both parents.

In contrast, mitosis is a process of cell division that produces two identical daughter cells, maintaining the same genetic material as the parent cell, and therefore does not contribute to genetic variation. Binary fission, typically seen in prokaryotic organisms, is a straightforward form of asexual reproduction and also results in offspring that are genetically identical to the parent. Cell differentiation refers to the process by which generic cells develop into distinct cell types with specialized functions, which does not inherently involve the mixing of genetic material that creates variability in offspring.