Answer:
The correct answers are: A single diseased cell can multiply into a new tumor; cancer cells can travel through the blood and spread into new areas; many cancer cells multiply so fast that new tumors can form.
Step-by-step explanation:
Cancer is the term that groups different conditions that have all one thing in common: there's an abnormal cell growth that can potentially irradiate to other parts of the body.
A single diseased cell can develop a tumor, because this abnormal cell has the capacity to replicate so fast and, of course, transmit its abnormality to every other cell that it generates.
These abnormalities occur because there is some sort of damage in the DNA of a cell, which most of the time is detected by the body and eliminated - but when it's not, the cell quickly multiplies itself and generates a tumor. The difference between a benign tumor and cancer is that cancer can spread through the body and a benign tumor can not.
Cancer is very dangerous and potentially fatal if not treated fast because it can travel through the bloodstream or the lymphatic system and invade other organs, causing metastasis.
There's a lot of research being done on how to cure cancer, but the disparities in every different type of cancer make finding the solution much harder. Nowadays, depending on the type of cancer and the stage where the cancer is, this condition can be treated with radiotherapy, chemotherapy, or surgery.