Which of the following best describes what happens during a cross-over event?

Chromatids of homologous chromosomes exchange corresponding segments.

Explanation:

The crossover of chromosomes is the exchange of genetic material between homologous chromosomes. Homologous chromosomes are present in the meiosis I, but not in meiosis the II. After pairing up of in the prophase I, homologous chromosomes are able to exchange some corresponding segments and a cross-over occurs. Thanks to the cross-over event, each chromosome will have a new combination of genes. Without this, parents will produce gametes with only two different gene combinations.

Chromatids of homologous chromosomes exchange corresponding segments.

image result for describe the various types of gene mutationsghr.nlm.nih.gov

the types of mutations include: missense mutation: this type of mutation is a change in one dna base pair that results in the substitution of one amino acid for another in the protein made by a gene. nonsense mutation: a nonsense mutation is also a change in one dna base pair.

explanation:

the offspring would all be white. if the parents are both white flowers then they have the genotype rr, which when crossed results in an all white punnet square.