Which of the following is NOT a stage of M phase?

The correct choice identifies interphase as not being a stage of M phase. M phase, also known as mitotic phase, consists of the stages involved in cell division, where the cell undergoes mitosis followed by cytokinesis. The stages of M phase include prophase, metaphase, anaphase, and telophase, each representing a distinct step in the process of cell division.

Interphase, on the other hand, is the phase that occurs before M phase and is primarily concerned with cell growth, DNA replication, and preparation for division. During interphase, the cell is not actively dividing; instead, it focuses on functions that maintain and enhance cellular operations, including the synthesis of proteins and organelles.

Therefore, pinpointing interphase as not part of M phase highlights its role as a preparatory phase, contrasting with the actively dividing stages of M phase. Understanding this distinction is essential in grasping the broader context of the cell cycle, where M phase is only a small part of the overall process of cell division.