The phase of mitosis in which sister chromatids move towards opposite poles:

Explanation

Anaphase is the most critical phase of the mitosis, which ensures equal distribution of chromatids in the daughter cells. The kinetochore fibers of spindle contract towards their respective poles, at the same time polar microtubules elongates exert force and sister chromatids are separated from centromere. As a result, half sister chromatids travel towards each pole.In metaphase, chromosomes line at the equator of the spindle. In prophase, chromosomes condense and the nuclear envelope disintegrates. In telophase, the sister chromatids have reached their respective poles and the two daughter nuclei form.