Answer: c. Phreatic eruption caused by the heating and expansion of groundwater.
Step-by-step explanation:
The Kilauea is an active volcano in Hawaii that erupted very violently due to the buildup of steam in 1924. Lava from the volcano usually drains back to the main magma body beneath the sea via a sort of passage. When this happens, water is able to enter the passage and instantly become steam when it interacts with the lava and escape up the volcano.
This time however, when the lava drained, the walls of the passage collapsed on the passage thereby blocking it. The water that had now come into contact with the lava and had become steam were trapped. The steam kept building up and eventually forced the rocks outward very violently resulting in the explosion.