The correct answer is option 1: cell division. Cancer is a disease characterized by the abnormal and uncontrolled growth of cells. In a healthy body, cell division is tightly regulated and only occurs when new cells are needed. However, in cancer, certain genetic mutations cause cells to divide and multiply uncontrollably. This results in the formation of a tumor or a mass of abnormal cells. If not treated, these cancer cells can spread to other parts of the body through a process called metastasis. It is important to note that while cell division is a key factor in the development of cancer, other changes within the cells, such as mutations and alterations in their function, can also contribute to the disease.