Around 1800 (plus or minus about 5 years) is when it was estimated that the world's population had reached 1 billion.
Erosion needs Earths rock
Erosion is wearing down and carrying away rocks by wind and moving water, happens faster with steep hillsides and heavy rain
They are farther away from the path of the sun. The equator is almost always directly in the pathway on the sun, while the poles aren’t.
I believe the awncer is B
Some of the US states that borders Canada are Minnesota, New York and Idaho