The correct option is C Only A, B and C
Uranium- 235 and Uranium-238 are abundantly used in nuclear reactors as they are fissile materials.
A radioactive isotope of iodine, iodine-131, has a half-life of eight days. It is employed in medicine to monitor thyroid gland functioning, to treat goitre and thyroid cancer, and to locate tumours of the brain and of the liver.
Cobalt-60 (Co-60 or 60Co) is a radioactive metal that is used in radiotherapy and Cobalt-57 (Co-57 or 57Co) is a radioactive metal that is used in medical tests.