The Great Rift Valley in Africa was created by .
A.
the movement of tectonic plates
B.
the spreading of the Sahara Desert
C.
the erosion of the Congo River
D.
the movement of glaciers during the last Ice Age

a. Movement of tectonic plates.

Explanation:

A.  the movement of tectonic plates

in the 1800s, chinese workers migrated to the united states, first to work in the gold mines, but also to take agricultural jobs, and factory work, especially in the garment industry. chinese immigrants were particularly instrumental in building railroads in the american west, and as chinese laborers grew successful in the united states, a number of them became entrepreneurs in their own right. as the numbers of chinese laborers increased, so did the strength of anti-chinese sentiment among other workers in the american economy. this finally resulted in legislation that aimed to limit future immigration of chinese workers to the united states, and threatened to sour diplomatic relations between the united states and china.