Identify the statement which is correct about radioactivity.

• A. Radioactive elements are dangerous because cells within the body preferentially incorporate radioactive atoms in their structures.
• B. Since radioactive elements have unstable nuclei, they all form cations due to the loss of electrons.
• C. Only those radioactive elements are dangerous which are artificial, naturally radioactive ones are safe.
• D. Energy released by radioactivity can break chemical bonds and therefore damage the delicate structure of cells within the body.

Answer: (D)