Chemotherapy is the correct answer. Chemotherapy is a treatment method that uses drugs to kill or slow down the growth of cancer cells. It is one of the main treatment options for cancer and is often used in combination with other treatments like surgery or radiation therapy. Chemotherapy drugs can be administered orally, through injections, or intravenously. These drugs work by targeting and attacking rapidly dividing cancer cells in the body. While chemotherapy can be effective in treating cancer, it may also cause side effects such as hair loss, nausea, and fatigue. It is important to note that physiotherapy, electrotherapy, and psychotherapy are not used as primary treatments for cancer. They may be used in some cases to manage symptoms or improve overall well-being, but they are not specific treatments for the disease.