What is the role of radioactive decay in dating fossils?

• A. It has no observable effect.
• B. Scientists analyze the level of radioactive decay within a fossil specimen to establish its age with high precision.
• C. It determines the fossil's color.
• D. It only works for plants.

Answer: (B)

Radioactive decay provides a clock for dating fossils. Scientists measure the amount of a parent radioactive isotope and its decay product in a specimen and use the known half-life to calculate how long has passed since the material formed. This approach can give ages with high precision under the right conditions, especially for organic material with carbon-14 (up to about 50,000 years) or for older samples using other isotopes such as potassium-argon or uranium-lead in the surrounding rock. The method relies on a predictable decay rate; contamination or using inappropriate materials can limit accuracy. The other statements misstate the method: radioactive decay is measurable and applicable to more than just plants or color, and it’s used on both organic material and rocks depending on the context.