The correct option is C Sr90
Sr90 is a radioactive isotope of strontium. It is formed in nuclear reactors or during the explosion of nuclear weapons. A large portion of this strontium accumulates in the bone. It behaves like calcium and mostly attaches to the surfaces of bones. This leads to cancer as a result of damage to the genetic material of the bone, nose, and lung and leukemia cells. Thus the correct answer is option C.