Aneuploidy, defined as an abnormal number of chromosomes, is the most common chromosomal abnormality. Which of the following events will result in Down syndrome, an example of a disorder caused by the inheritance of an extra chromosome 21? Group of answer choices the nondisjunction of this set of homologues during meiosis II the failure of two sets of homologous chromosomes to line up properly during metaphase I the incorrect separation of this pair of sister chromatids during meiosis II a crossing over of genetic information between homologous chromosomes during prophase I.

The correct answer is - the incorrect separation of this pair of sister chromatids during meiosis II.

Explanation:

Down syndrome is a type of aneuploidy in which the number of the chromosome is not as normal condition as it occurs by inheritance of an extra chromosome. This disorder is usually caused due to an error or in meiosis if the sister chromatids fail to separate during meiosis II in an embryo and leads to three copies of the chromosome instead of two.

This condition is lead to the down syndrome which is one of the most common trisomy case as it results an extra chromosome of chromosome 21.

Thus, the correct answer is - the incorrect separation of this pair of sister chromatids during meiosis II.