C) 30 miles is the correct answer
(I’m not sure but I think so)
One reason is that the plates float on a hot boiling mentle. when the heat rises and the mentle expands the plates above it also moves.
the other reason is that the plates themselves move.plates have warmer inner sides that tend to rise. and colder outer side that tends to sink. this tug of war between the hotter and colder sides of the plate also helps them move.
<span>a reference point for measuring elevation</span>
More likely the answer A if it not im sorry
A slow change to the earth's surface would be the formation of mountain ranges over millions of years due to the shifting of tectonic plates under the earth. Also, another slow change could be considered erosion or weathering. Two rapid changes could be landslides and earthquakes.