Radioactive cobalt-60 is used in radiation therapy treatment. Cobalt-60 undergoes beta decay. This type of nuclear reaction is called

(1) natural transmutation

(2) artificial transmutation

(3) nuclear fusion

(4) nuclear fission

The answer is (1) natural transmutation. When Co-60 undergoes beta decay (be it beta positive or beta negative), the product is another element (Fe or Ni). Transmutation is when an element turns into another element via a nuclear process. Since this occurs without the aid of another agent that causes the nuclear change (e. g. a neutron source), it is natural transmutation.