The correct option is A. Ash layers from the three most recent caldera-forming eruptions at Yellowstone 2.1, million years ago stretch one side of Yellowstone national park to the other.
Releasing of lava and gases from the volcano is called a Volcanic eruption. They are generally explosive. They can travel quickly and reaches a temperature of 1,200-degree Fahrenheit.
Thus, 2.1, million years ago the ash layers eruption at from one side of Yellowstone national park to the other.
Learn more about Volcanic eruptions here:
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