OG4 阅读 Q44

Choice A is the best answer. In lines 17-25("In ......C.E."), the passage shifts focus from describing a recorded event to providing evidence that the Little Ice Age was likely caused by a volcanic eruption. The passage states that scientists used "radiocarbon dating of dead plant material from beneath the ice caps on Baffin Island and Iceland, as well as ice and sediment core data" to determine when the Little Ice Age began and how it was connected to the "mystery" volcanic eruption.
Choices B, C, and D are incorrect because they do not provide the best evidence that the passage shifts focus from a description of a recorded event to its likely cause. Choices B, C, and D all focus on the scientists' research but do not explain what caused the Little Ice Age.