Which of the following does not explain why radioactive strontium is used in treating bone cancer?

• A. Radioactive strontium is similar to calcium which is a component of bones, so it is also absorbed by normal bone cells and cancer cells.
• B. Radioactive strontium emits beta radiation that kills cancer cells or slows their growth by damaging their DNA.
• C. Radioactive calcium is rarely found.
• D. Radioactive strontium undergoes beta decay which irradiates bone marrow cells.

Answer: (C)