They got to know with the photographs from the U - 2 spy plane.
<em>Hope this helped! :)</em>
If these are the options:
<span>- They followed the Mississippi from its source to its mouth.
- They claimed large stretches of land in the southern U.S.
- They claimed the St. Lawrence River.
- Spain gained great wealth.
The answer would be SPAIN GAINED GREAT WEALTH.
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I believe the third answer is the correct one
Which of the following describes one of the Mongol Empire's major economic accomplishments?
A. The Mongol Empire was the first large state to introduce paper money.
B. The Mongol Empire plundered the territories it captured, devastating the economies of entire regions.
C. The Mongol Empire was led by rural farmers and converted its conquered territory to farmland.
D. The Mongol Empire guarded roads carefully to promote trade throughout its territory.
The answer is D.