They really help in the process of Africa's state building, creating commercial networks between parts of the continent, and introducing literacy ( especially on northern part of Africa)
They also controlled the sea route between Asia and Africa and managed to maintain the relationship between Africa and the middle east
I think the answer would be C) a place where water heated by magma rises from the ocean floor because it is an opening on the Ocean floor that releases heated mineral - rich water.
Answer:
Remember that perimeter is the measure of the outer edge of a shape, or otherwise, the sum of the measures of the sides of the trapezoid. Representing the perimeter by P, and the sides as a, b, c and d, our formula is P = a + b + c + d.