Which statement best explains how hotspots inform plate motion history?

• A. Hotspots are fixed mantle plumes that create volcanoes as plates move over them; a chain of volcanoes forms as the plate moves, recording its path.
• B. Hotspots move with the plates and leave no track.
• C. Hotspots form only at plate boundaries.
• D. Hotspots have no relation to plate motion.

Answer: (A)

Hotspots arise from deep mantle plumes that stay essentially fixed while the tectonic plates above them move. As a plate drifts over a stationary hotspot, a volcano forms; when the plate has moved away, a new volcano develops over the plume. Over time this creates a linear chain of volcanoes and seamounts that records the past position of the plate. Dating the features along the chain shows an age progression toward the current hotspot, revealing the direction and rate of plate motion in the past. So hotspots inform plate motion history by providing a persistent reference point that the moving plate leaves a trail around. The idea that hotspots move with the plates is incorrect; hotspots can form away from plate boundaries and still record motion, and they are not unrelated to plate dynamics.