During 1200 to 1450, Timbuktu had the largest library in the world and it held hundreds of thousands of books. Their library brought them great wealth and prosperity. However, after Chris Columbus and his Spanish explorers discovered the Americas and eventually started the Columbian Exchange, Africans were greatly disadvantaged. The Europeans captured millions of West Africans and transported them to the Americas as slaves. Timbuktu was located in West Africa. Their library is their biggest token of wealth after all the horror all the enslaved West Africans went through.
Apartheid was a system of institutionalized racial segregation and discrimination of South Africa during 1948 and 1994
The major developments in transportation were that overland transportation was improved by the creation of the National Road, the speed of water transportation was improved by the steamboat that made it easier to travel against the current, new canals provided efficient water transportation that linked farms to expanding cities, and railroads were built which cost less to build, could scale hills easier, moved faster than ships, and carried more weight.
This let people travel further distances for work. Leading to more towns staying stable as if people lived in one location they could take the rivers or railroad to get to the work camps and such. As prior to these developments people had to move where work was located this wasn’t required anymore. As well as this gave thousands of jobs and let jobs be more stable.
I believe the answer is 4. During the reign of Askia Muhammad, the Songhai empire reached its greatest size.
Askia Muhammad was an emperor, military commander, and political reformer of the Songhai Empire in the 15th century. His rule resulted in trade with Europe and Asia, building of lots of schools, and spread of Islam through his empire.
Hope this helps! Please let me know if I'm wrong :)