What’s the difference between Bear market & Bull market? Explain isolationism

This emblem shows a jewish star inside a shape that combines a fortress and a shield.

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.

Which best describes the impact of the crusades on european exploration?