In which mitotic phase are the sister chromatids separated and pulled to opposite poles?

Anaphase would be the correct answer. So you know anaphase is the shortest phase of mitosis; because literally all that happens is chromatids are pulled to polar opposite sides of the cell. All the work for this phase is completed in metaphase when spindle fibers (microtubules) grow from the centrioles and bind to the kinetochores of the chromosome.