Final answer:
Pillow lavas are formed when lava emitted from underwater volcanic eruptions cools rapidly upon contact with water, creating rounded pillow-like shapes.
Step-by-step explanation:
The correct answer to the question is C. Pillow lavas. These are unique geological formations that are created when lava flows from a volcanic eruption into water. As the hot lava encounters the water, it cools rapidly, forming rounded lobes that resemble pillows.
The water gets trapped between these lobes and rises, causing the surrounding lava to cool quickly. This process results in the characteristic pillow-like shapes. Pillow lavas are especially common in underwater volcanic eruptions, such as at mid-ocean ridges where new oceanic crust is formed. The formation of pillow lavas provides insight into the complex interactions between lava and water, as well as the conditions present during underwater volcanic activity.