Answer;
A. In anaphase I, homologous pairs are separated but sister chromatids stay joined together.
Step-by-step explanation;
-Anaphase of mitosis is stage during during which each chromosome's sister chromatids separate and move to opposite poles of the cell. The stage before anaphase, metaphase, the chromosomes are pulled to the metaphase plate, in the middle of the cell.
-Anaphase I begins when the two chromosomes of each bivalent (tetrad) separate and start moving toward opposite poles of the cell as a result of the action of the spindle. The sister chromatids remain attached at their centromeres and move together toward the poles.