The U.S politicians and businessmen worried about the foreign nations controlled economic development so they supported open door policy
There are 3 feet in 1 yard. you would multiply any given number of yards by 3 in order to get how many feet it contains. in this case:
there are 120 feet in 40 yards
Answer: C. horse and buggy
Explanation: From about 1811-1840 the Oregon Trail was laid down by traders and fur trappers. It could only be traveled by horseback or on foot. By the year 1836, the first of the migrant train of wagons was put together.
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It's not A, as they simply aren't forced to.
It's not C, as Africa is not 'just' a colony; infact, empires and therefore colonies are no longer allowed among the UN.
D is incredibly stupid.
So, B.