Combination of alleles that independently assort is usually higher than the number of chromosomes because of:A. segregation. B. jumping genes. C. gene linkage. D. crossing over. E. translocation.

D. Crossing over

Explanation:

During prophase-I of meiosis-I, a process of genetic recombination occurs. During this process, two non-sister chromatids of the paired homologous chromosomes exchange a part of the genetic segment. This is called crossing over. Crossing over results in the production of recombinant chromatids that carry new combinations of alleles that were otherwise not present in the parental chromosomes. Therefore, crossing over generates some extra combinations of alleles.