Which one of the following is used in the treatment of blood cancer?

Correct answer: (d) Cobalt - 60

Explanation

Cobalt-60 is a radioactive isotope that emits high-energy gamma rays, used in radiotherapy for blood cancer (leukemia).

Iodine-131 treats thyroid disorders, Sodium-24 traces blood circulation, and Phosphorus-32 is used in some bone/skin cancer studies.