Choice B is the best answer. The author begins the passage by explaining how the Little Ice Age was a "centuries-long cold snap" that was likely caused by a volcanic eruption (lines 1-3,"About ...Ice Age"). The author then explains how scientists used radiocarbon analysis to determine when the Little Ice Age began and how a volcanic eruption triggered the cooling temperatures (lines 17-25,"In 2012...1455 C.E").
Choices A, C, and D are incorrect because the passage does not criticize a scientific model, offer a new method of measuring sulfates, or shift from the use of radiocarbon dating to an examination of volcanic glass.