The splitting of centromeres takes place during
Prophase is marked by condensation of chromatin fibers and presence of visible sister chromatids of each chromosome. Metaphase is marked by alignment of duplicated chromosomes on the equatorial plate. Anaphase is marked by splitting of centromere and contraction of spindle fibers which in turn move the sister chromatids towards the opposite poles. Telophase is marked by the presence of daughter chromatids at the opposite poles. Cytokinesis is the division of cytoplasm that takes place after karyokinesis. So, the correct answer is A.