The eruption intensified the greenhouse effect. Lava flow from the eruption caused a temporary increase in Earth's total heat energy. The eruption caused damage to the ozone layer. Air pollution from the eruption caused a decrease in the amount of solar energy reaching Earth.
I gave my students this multiple choice question: Nearly 100 years ago, a large volcano erupted in the South Pacific. The following year, Boston recorded measurable snow every month of the year, and most of the Northern Hemisphere experienced a cold summer. Which explains how these two events were related?

Only one answer is correct among these 4 choices:
- The eruption intensified the greenhouse effect.
- Lava flow from the eruption caused a temporary increase in Earth's total heat energy.
- The eruption caused damage to the ozone layer.
- Air pollution from the eruption caused a decrease in the amount of solar energy reaching Earth.

Could you tell me which one is correct?

Air pollution from the eruption caused a decrease in the amount of solar energy reaching Earth.