The following text discusses archaeological dating methods.
Radiocarbon dating revolutionized archaeology by providing absolute dates for organic materials. The technique measures the decay of carbon-14, which organisms absorb during their lifetimes. After death, this radioactive isotope decays at a known rate, creating a measurable "clock." The method's accuracy diminishes beyond approximately 50,000 years, requiring other techniques for older materials.
What is the main purpose of the text?
To argue for increased funding of archaeological research
To compare radiocarbon dating with alternative methods in detail
To explain how radiocarbon dating works and note its limits
To profile the scientists who developed the technique
Correct Answer: C
Choice C is the best answer. The text explains how the technique works (carbon-14 decay) and notes its limits (accuracy diminishes after 50,000 years).
- Evidence: The text explains the mechanism: "measures the decay of carbon-14," "measurable 'clock'." It notes limits: "accuracy diminishes beyond approximately 50,000 years."
- Reasoning: The passage is a scientific explanation that covers both the method and its boundary conditions.
- Conclusion: The purpose is to explain the method and limits.
💡 Strategy: Summarize: How it works + When it stops working.
Choice A is incorrect because funding isn't discussed. Choice B is incorrect because alternatives aren't compared in detail. Choice D is incorrect because scientists aren't profiled.