What process occurs during crossing-over in meiosis?

During crossing-over in meiosis, the exchange of chromosomal segments occurs between homologous chromosomes. This process takes place during prophase I of meiosis, where homologous chromosomes come together to form pairs in a structure known as a tetrad. As they align closely, segments of DNA are exchanged between the paired chromosomes. This genetic recombination increases genetic diversity in the resulting gametes, which is a fundamental aspect of sexual reproduction. The significance of this process is that it allows for new combinations of alleles, contributing to the variation that is essential for evolution and adaptation in populations. The other choices involve different stages or processes related to cell division but do not pertain to the specific event of crossing-over.