Q: Which instruments are used to measure the angle of the slope of a volcano?


Read this paragraph and choose the correct option from the provided answers:

All that magma and gas pushing upwards can make the volcano’s slope begin to swell. Ground swelling may change the shape of a volcano or cause rock falls and landslides. Most of the time, the ground tilting is not visible. Scientists detect it by using tiltmeters, which are instruments that measure the angle of the slope of a volcano.

 Choices:

- altimeter

- compass

- calipers

- tiltmeters


A:
tiltmeters