After reaching North America, humans migrated to South America.
I think the answer is D) Medicine.
Hope this helps!
Answer:
Stream gradient refers to the slope of the stream's channel .It is the vertical drop of the stream over a horizontal distance.
Explanation:
Gradient is the slope or steepness of a stream channel. It affects the stream's velocity because the steeper the gradient is the greater the velocity due to gravity.
<span>When
the water level of a stream or river exceeds its natural banks, it has reached
its flood stage. This is a real panic stage for people living nearby the rivers
and streams that has overflowed its natural banks. This flood situation can
destroy any city or village and also drastically impact the financial situation
of the area. Most cities and states move their citizens away from the river
banks before it reaches this danger stage. Before the emergence of
technological advancement, historical evidence proves that many great cities
were destroyed due to such situations. <span /></span>
