What occurs during mitosis?

Mitosis is a process of cell division that results in two genetically identical daughter cells, each with the same number of chromosomes as the parent cell. During mitosis, the nucleus undergoes a series of stages where the copied chromosomes align, separate, and are distributed into two new nuclei. This ensures that each daughter cell receives an exact copy of the genetic material.

The correct answer highlights the key aspects of mitosis: the crucial role of the nucleus in copying chromosomes and the final step of dividing the nucleus to create two cells. This process is fundamental to growth, repair, and asexual reproduction in organisms.

The other choices do not accurately describe mitosis. While option B mentions the duplication and division of chromosomes, it incorrectly implies that division happens twice, which is a characteristic of meiosis, not mitosis. Option C refers to the transformation into specialized types of cells, which is related to differentiation, not the straightforward division of mitosis. Option D discusses mutations, which can occur in cells but are not a defining aspect of the mitotic process itself. Therefore, the correct understanding of mitosis focuses on the duplication and splitting of chromosomes within the nucleus, resulting in two new cells.