In Early Prophase, which occurs?

• A. Nuclear envelope breaks up, allowing the spindle to interact with the chromosomes
• B. The nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes
• C. In this subphase of cell division, chromosomes become visible, centrosomes separate and migrate toward opposite poles and mitotic spindles and asters form
• D. Chromosomes line up in the middle of the cell

Answer: (C)

In early prophase, chromosomes condense and become visible as distinct structures, signaling the start of chromosomal condensation. At the same time, the centrosomes separate and migrate toward opposite poles, and the mitotic spindle begins to assemble with spindle fibers and asters forming. The nuclear envelope remains intact at this stage, and kinetochores have not yet attached to spindle microtubules; those events occur later, as the envelope breaks down in prometaphase. Chromosomes lining up in the middle of the cell is a later event, characteristic of metaphase.