Dendrochronologists analyze the annual growth rings of ancient trees to reconstruct historical climate variations. In a recent study of subalpine conifers in the Sierra Nevada, researchers observed a series of unusually narrow and frost-damaged rings dating to the mid-sixth century CE. The researchers hypothesized that this stunted growth was caused by a major volcanic eruption that released sunlight-blocking sulfate aerosols into the atmosphere, leading to a decade of colder summers. To test this hypothesis, they compared their tree-ring data with ice core samples from Greenland, which revealed a corresponding spike in volcanic ash from the exact same period, thereby confirming the volcanic trigger.
Which choice best describes the overall structure of the text?
- AIt details a historical debate, explains two contrasting methods of investigation, and argues that one method is superior.
- BIt explains a common biological technique, identifies its main limitation, and proposes a solution to overcome it.
- It introduces a scientific observation, outlines a hypothesis proposed to explain it, and describes a comparison used to support that hypothesis.Cevap
- DIt presents a general ecological principle, describes how it was discovered, and lists its modern applications.