Which of the following is a stage of mitosis?

• A. Interphase
• B. Prometaphase
• C. Cytokinesis
• D. Telophase

Answer: (B)

Prometaphase is a stage of mitosis defined by the breakdown of the nuclear envelope and the attachment of spindle microtubules to kinetochores, which lets condensed chromosomes start moving toward the center of the cell. This period comes after prophase and before metaphase, serving as the transition where chromosomes become properly aligned for segregation. Interphase is the cell-cycle phase before mitosis, focused on growth and DNA replication, so it isn’t a mitotic stage. Cytokinesis happens after mitosis, dividing the cytoplasm to complete cell division, and while Telophase is indeed another mitotic stage, promont阶段 specifically marks the key events of chromosome attachment and movement that define mitotic progression from prophase toward metaphase.