After almost ten years on the march what caused alexander to turn back

Prior to the presence of europeans on the continent, the slave trade in africa a) did not exist in any form. b) was limited to internal trade only. c) included the trans-saharan and indian ocean slave trade. d) was rarely needed due to the lack of an agricultural economy.

How did the magna carta affect the power of the english king? a) it closely linked the king's power to the power of the nobles. b) it weakened the king's power. c) it strengthened the king's power. d) it had no effect on the king's power.

What were two theories put forth by marx?