Final answer:
Anaphase II of meiosis II involves the separation of sister chromatids and the formation of four unique haploid cells.
Step-by-step explanation:
The phase of meiosis that involves the separation of sister chromatids is anaphase II of meiosis II. In anaphase II, the sister chromatids separate and move to opposite poles of the cell, resulting in the formation of four unique haploid cells. During this process, each chromosome becomes composed of two identical copies (sister chromatids) that are held together at the centromere until they are pulled apart.