Answer:
I think its gravity but not sure
Answer:
The method that scientists use to discern this information is similar to medical CT scans that bounce X-rays through the human body to make three-dimensional pictures of internal tissue. In an analogous manner, a method called seismic tomography uses hundreds to thousands of earthquakes recorded by dozens of stations to measure the speed of seismic waves through the Earth--data that allow geophysicists to make three-dimensional pictures of structures beneath the surface. Scientists compare these seismic velocities and infer the composition by comparing them with average, thermally undisturbed values.
Explanation:
Answer:
D. Enabled the transportation of goods from the interior of Canada
