Pls help me with 4 questions... Pics included

How might reuionfucation of east and west germany in 1990 have been imporant turning point for the soilvet union

Which factor contributed to the rise of african empires such as ghana and mali ? a. their creation and involvement in trade networks b. they focused only on agricultural production. c. they didn’t engage in warfare with other nations d. their geographic location protected them from attacks.

From where do ocean waves obtain their energy