Well for the very last sentence it would be if any of the organs shut down it could seriously hurt someone or possibly even kill them if their brain,heart or some other important organ shuts down it could kill them.
There are other minor organs where if it shuts down it wouldn't really hurt the person too much. Sorry I couldn't help you with the other ones though.
Answer:
I think it is A. Metaphase
For if it is proved wrong you can retry.
When cell division is not regulated it can cause a malignant rumour called cancer , radiation is used in chemotherapy to kill the cancer, tumoutsd can also be benign