The separation of sister chromatids is the only item of the answer choices that occurs in both mitosis and meiosis. Prophase II and metaphase II only occur in meiosis, as does recombination between homologous chromosomes. Recombination between sister chromatids does not occur (they are identical).

Since the cell has 44 autosomes and two sex chromosomes it must be a somatic cell (2n=46). Two X chromosomes corresponds to a female so it must a somatic cell from a female. Sperm, and ova are the male and female gametes, which are haploid.

Meiosis is the form of cell division that results in gametes and so meiosis takes place in both ovaries and testes, which are the primary sex organs. Somatic cells undergo mitosis for cell division, which yields identical daughter cells that are diploid.  

Gametes are haploid cells that produced via meiosis. During meiosis, diploid cells divide into four nonidentical haploid daughter cells. Mitosis produces two identical diploid somatic cells from one parent cell.  

Meiosis results in cells with 23 chromosomes (22 autosomes and 1 sex chromosome). Note that these cells are haploid since n=23, and nonidentical, due to crossing over during prophase I.

Gametes are made via meiosis which produces cells with n=23 instead of diploid cells. If gametes were produced instead by mitosis each gamete would be diploid not haploid. During fertilization of diploid gametes, the zygote would become 4n=92. With each new generation the number of chromosomes would double.  

In biology, the term “ploidy” refers to the number of chromosome sets per cell. Haploid cells have half of the number of chromosomes as parent cells, meaning that they only carry a single copy of each gene. Haploid cells are formed during meiosis and, in humans, produce gametes, which mature into sperm and egg cells.

Diploid cells contain two copies of each chromosome, therefore containing twice as many (2n) chromosomes as a haploid cell (n), which contain only one copy of each chromosome. In humans, diploid somatic cells contain 46 chromosomes, or 23 pairs of chromosomes.

Trisomy 21, or Down syndrome results when a human individual inherits three copies of chromosome 21, instead of the normal two copies (one maternal and one paternal). This is caused by nondisjunction, or the improper segregation of chromosomes during cell division. In the case of trisomy 21, nondisjunction leads to a failure of chromosome 21 segregation during meiosis (most of the time during anaphase I). This results in either an egg or sperm carrying two copies of chromosome 21 instead of one. The zygote formed by fertilization develops into an individual that has three copies of chromosome 21. Trisomy 21 manifests in physical growth delays, intellectual disabilities, and distinctive facial features. 

Nondisjunction is the improper segregation of chromosomes during meiosis or mitosis. The molecular causes behind nondisjunction are (1) increased rate of nondisjunction in female cells, (2) failure to properly pass the spindle assembly checkpoint, and (3) weakening of the cohesion complex at the centromere due to age.