What was the name given to the series of caliphs, who ruled over the Arabs, after the death of the prophet?

After Prophet Muhammad's death, the rulers of the Islamic community were called Caliphs (Khalifas), meaning "successors" or "deputies." The Caliphate system spanned from 632 CE through various dynasties including the Rashidun, Umayyad, and Abbasid. While the question is somewhat tautological (asking the name of a series of caliphs), option B is the correct historical term for these political-religious leaders.