______ refers to the radioactive decay of different discrete radioactive decay products as a chained series of transformations.

• A. Nuclear chain reaction
• B. Half-life series
• C. Spontaneous fission cascade
• D. Decay Chain (or Radioactive Cascades)

Answer: (D)

Decay chain is the sequence in which a radioactive nucleus decays to a daughter that is itself radioactive and then decays again, continuing in a chained series of transformations until a stable nuclide is reached. Each step is a discrete decay with its own characteristic rate, so you end up with a cascade of different radioactive products rather than a single event. This description captures why the term fits: it describes how the original parent is transformed through successive decays of distinct products, forming a chain or cascade of radioactive species. This is different from a nuclear chain reaction, which involves neutrons causing fission in other nuclei, not a sequence of decays; and terms like half-life series or spontaneous fission cascade do not describe the recurring, stepwise transformation of decay products toward stability.