Geologists installed tiltmeters in a tectonically active area. Tiltmeters can detect very small changes in the slope (tilt) of Earth’s surface. These changes result from the upward movement of magma beneath Earth’s surface.
What event could be predicted by monitoring these changes?
A. a potential volcanic eruption
B. reversal of Earth’s magnetic field
C. a change in the composition of Earth’s crust
D. decreased thermal energy transfer within Earth

Question

Geologists installed tiltmeters in a tectonically active area. Tiltmeters can detect very small changes in the slope (tilt) of Earth’s surface. These changes result from the upward movement of magma beneath Earth’s surface. 
What event could be predicted by monitoring these changes?      
A.	a potential volcanic eruption 
B.	reversal of Earth’s magnetic field 
C.	a change in the composition of Earth’s crust 
D.	decreased thermal energy transfer within Earth