Correct Answer:
C. Carbon-14.
Explanation:
The correct answer is Carbon-14. because it is a radioactive isotope used to determine the age of organic materials.
- Step 1 (Radioactive Decay): Carbon-14 is an unstable, radioactive isotope of carbon that decays over time with a predictable half-life of approximately 5,730 years. Organisms absorb it during their lifetimes, and measuring its remaining amount after death allows scientists to accurately calculate elapsed time.
- Step 2 (Dating Range): Because of its specific decay rate, this isotope is ideal for dating archaeological and organic samples up to roughly 50,000 years old.
- Incorrect Options:
- Carbon-12 is incorrect because it is the most common stable isotope of carbon and does not undergo radioactive decay, making it useless for tracking time.
- Carbon-13 is incorrect because it is also a stable isotope of carbon that does not decay over time.
- Carbon-15 is incorrect because it is a highly unstable synthetic isotope with a half-life of less than 2.5 seconds, meaning it vanishes too quickly to be found in nature.