Which of these choices is not one of the phases of mitosis?

The correct answer is Diplophase. This is because Diplophase is not one of the phases of mitosis. The phases of mitosis are prophase, metaphase, anaphase, and telophase, which are all involved in the division of the nucleus during cell division. Diplophase, on the other hand, refers to the diploid phase of the cell cycle, which involves the replication of DNA and occurs during the interphase, not during mitosis specifically. Thus, Diplophase is unrelated to the process of mitosis and is not considered one of its phases.