The most powerful African kingdom was "The Songhai Empire" which was a pre-colonial West African trading state;
(<em>the first African kingdom to trade</em>)
dominating around the 15th and 16th century and extending from the Atlantic coast all the way through Niger and Nigeria, controlling the <em>gold and salt trade</em>, conquering the Mali Empire, and absorbing main cities such as Gao and Timbuktu.
The empire started its decline after "<em>The Battle of Tondibi</em>" under a Moroccan army in the late 16th century.
I might be wrong but I believe it's either A or D.
Scientists use scientific thinking to test hypotheses
Yeah it's B. The Pentagon papers were leaked and showed that the US was involved with the Vietnam war far longer than the public thought.
Upon Lenin's death, Stalin was officially hailed as his successor as the leader of the ruling Communist Party and of the Soviet Union itself.
