Sister chromatids are separated during Meiosis II and Mitosis. Therefore, the correct answer is d) Meiosis II and Mitosis.
During cell division, sister chromatids are initially joined together after DNA replication. In the case of mitosis, the cell goes through prophase, metaphase, anaphase, and telophase. It is during anaphase that the sister chromatids are pulled apart to opposite poles of the cell.
In meiosis, which consists of two rounds of division, sister chromatids are also separated during Meiosis II in a similar manner to mitosis. After Meiosis I, homologous chromosomes are separated, but sister chromatids remain attached until Meiosis II, when they are finally separated during anaphase II.
Thus, understanding the context of these processes clarifies that sister chromatids are only separated in the final stages of both meiosis and mitosis.