It is A because the north were offering jobs to the blacks down south, most of them took as a chance to move to a more equal and calm society without racism.
Unrestricted submarine warfare, which became prominent in World War I, meant that submarines could sink any time of vessel at any time without warning. Before this, they had to surface first and place crews on lifeboats.
<span>According
to Bernstein, the specific prediction in the "Communist Manifesto"
that failed to materialize is the prediction about the “coming”. This is also
the common prediction of the millennialism that also failed to materialize. This
is an old prediction in which many people believe but it did not happen yet.</span>
The answer is option 3: A technique for making porcelain was perfected.
The art of making porcelain prospered in both periods. A lot of innovations were made in forms, glazes, decorative techniques methods of production and kiln technology.
During the Tang Dynasty, porcelain kilns were constructed all over the country and a type of vessel with molded decorations on it became very popular, which was made using an "upside down" and the coal was used as kiln fuel.
By the Song period, the manufacturing process was standardized (base-making, glazing, ingredient control, and temperature maintenance). In addition, the industry was divided into five types of kilns that had several features for glaze coloring and pattern design.
