The answer is c,d,a those are the correct answers
Answer:
Medina
The time period under the leadership of the Four Caliphs is called the Rashidun Caliphate by historians. The Rashidun Caliphate lasted for 30 years from 632 CE to 661 CE. It was followed by the Umayyad Caliphate. The city of Medina served as the first capital of the Caliphate.
One step was that Abraham Lincoln signed the Emancipation Proclamation, making slavery illegal in the United States.
The answer is thought that experts would help make government more efficient.
