What is metastasis? 

A)  the process of dying from cancer 
B)  the result of coming into contact with a carcinogen 
C)  the surgical removal of a tumour 
D)  when malignant cells break off from tumours to other parts of the body

Metastasis is the spread of malignant cells from a primary tumour to other parts of the body, often through the bloodstream or lymphatic system. It is a key characteristic of cancer and one of the main reasons for its lethality. A carcinogen, on the other hand, is a substance or agent that can cause cancer by damaging DNA or other vital molecules in cells. Surgical removal of a tumour may be a treatment option if it is feasible and if the cancer has not spread too far, but it does not guarantee a cure or prevent metastasis. Finally, dying from cancer is a possible outcome, but not all cancers lead to death and not all deaths from cancer are due to metastasis.