Answer:
Prophase
Explanation:Because at the beginning of active cell division, there are many events taking place. This first part of mitosis is called prophase. One of the first visible signs of mitosis is a shortening and thickening of each DNA chromatin, which now appear as a single strand or rod. As the chromatin shortens and thickens, it forms distinct chromosomes. Each chromosome pair consists of two identical rods of genetic material called sister chromatids, which are attached by a centromere.