Mt. St. Helens erupted explosively in 1980. Geologists find evidence of many eruptions of St. Helens, dating back 37,000 years. The mountain is huge and is composed of layers of

lava and pyroclastic debris. Which of the following is, therefore, most likely to be true? A. Mt. St. Helens sits on a transform-plate boundary. B. The volcano is extinct. C. When lava flows from Mt. St. Helens, it will be basalt. D. Mt. St. Helens is a stratovolcano (or composite volcano).

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