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.
I’m pretty sure you just add AB to BC, since they are all points on a line, those two segments add together to get the value of AC. Therefore, 12+16= 28, so AC=28
A ruby is a gem not a mineral :)
Northern Ireland is separate from Ireland because 90 years ago people living in Ireland had a war against the British rulers. That's how Northern Ireland split from Ireland.
Hope this Helps!
Answer:
a. They must be present in a large geographic area.
Explanation:
Index fossils can be used to determine the age of a rock strata with great precision, but they must be scattered over a large geographic area to be able to be used reliable for this type of measurement. Index fossils typically indicate a certain type of paleoenvironment belonging to a very specific prehistoric period and their formation coincides with the age of the rock layer.
