The correct answer is d) anaphase II.
During meiosis, sister chromatids are separated in anaphase II, which is the stage following metaphase II and telophase I. In anaphase I, homologous chromosomes are separated, but the sister chromatids remain attached. It is only during anaphase II that the connections holding the sister chromatids together are broken, allowing them to move to opposite poles of the cell. This separation is essential for ensuring that each gamete ends up with the correct number of chromosomes.