Answer:C. To prepare for potential conflict with the Soviet Union
Explanation:
Responding to xenophobic concerns, Congress passed an emergency law restricting immigration in 1921. Among other provisions, the Act established a quota (a proportional share of a total) for nationalities on the basis of their numbers in the U.S. in 1910.
The missing detail is: a quota.
<span>The Wall served to prevent the massive </span>emigration and defection<span> that had marked East Germany and the communist Eastern Bloc during the post-World War 2 period.</span>
The steam engine of Thomas Newcomen and James Watt used the same principle of creating a vacuum and using steam to drive the device. The difference is that in James Watt's version, he uses a separate condenser to allow for a much greater efficiency in terms of power. The main difference with a separate condenser is that with a separate condenser, the main device can remain hot at all times, thus increasing efficiency.