C. OAU. Organization of African Unity (OAU) had nothing to do with America.
1. It spread through trade with other countries. As merchants came into Africa, they not only traded goods, but also cultures. They taught the Africans about the Muslim teachings and many Africans ended up adopting it.
2. It spread through migration. As Africans migrated from one side of the continent to another, they brought with them their religion and shared it with the people who were living in the places they migrated to.
The Code of Hammurabi can tell us much about ancient Babylonian society, but cannot show us everything. The law code was written for the audience of Babylonian people in its own day, especially the scribes and officers of the law. So there are many questions we would have from a distance much later in history that people then would have understood without needing explanation. The intention of the law code was to inform people of laws and punishments, not to give later generations a full view of the whole of Babylonian life. The law code was prepared by those in power in the government of Hammurabi -- we don't get any response from the people or indication of how the people then viewed the laws. And ultimately, the law code is written in a detached, impersonal way -- as legal documents generally are written. We don't get a feel for the personal lives or feelings of people living at that time in Babylonia.
The League of Nations was formed to unify many countries. It wasn't very efficient. The United Nations was essentially an improved version of the League of Nations.