1. The problem asks to identify the stage of mitosis shown in the photomicrograph of onion root tip cells. 2. The stages of mitosis include Prophase, Metaphase, Anaphase, and Telophase. 3. In Anaphase, chromosomes separate and move toward opposite poles of the cell. 4. The arrow points to a cell where chromosomes appear separated and moving apart, which matches the description of Anaphase. 5. Therefore, the correct answer is Anaphase.