Answer:
A. increased; Great Migration
Explanation:
When the migration began, 90 percent of all African-Americans were living in the South. By the time it was over, in the 1970s, 47 percent of all African-Americans were living in the North and West. A rural people had become urban, and a Southern people had spread themselves all over the nation.
Saturn is predominately composed of hydrogen and helium, yet doesn't undergo fusion like the Sun due to the lacking mass.
Continental drift is the name of this theory.
The answer to your question is A
Continuous deposition (or deposition)
