Meiosis I is reductional division and meiosis II is equational division because of

The correct option is Separation of chromatids.

To understand why meiosis I is reductional division and meiosis II is equational division, let us break down the behavior of chromosomes and chromatids during both divisions:

1. Meiosis I (Reductional Division):
During meiosis I, homologous chromosomes pair up and then segregate. In anaphase I, homologous chromosomes separate and move to opposite poles of the cell, but the sister chromatids remain attached at their centromeres. As a result, the chromosome number is halved from diploid (2n) to haploid (n). Because the chromosome number is reduced, meiosis I is called a reductional division.

2. Meiosis II (Equational Division):
Meiosis II resembles a normal mitotic division. During anaphase II, the centromeres split, leading to the separation of sister chromatids. Each chromatid now becomes an individual chromosome. These separated chromatids move to opposite poles. Because the number of chromosomes remains the same before and after meiosis II (haploid to haploid), it is called an equational division.

Therefore, the transition from a division that reduces chromosome number (meiosis I) to one that maintains the ploidy level by dividing the genetic material equally (meiosis II) is specifically due to the separation of chromatids during meiosis II.