The correct option is
C Stephan
Stephan's predecessor Henry I of England (r. 1100-1135 CE) had left no male heir and his nominated successor, his daughter Empress Matilda, was not to the liking of many powerful barons who preferred Stephen, the wealthiest man in England and nephew of Henry I.
When Henry I died at Lyons-la-Forêt in eastern Normandy, his favourite nephew, Stephen of Blois, disregarding Matilda’s right of succession, seized the English throne. Matilda’s subsequent invasion of England unleashed a bitter civil war that ended with King Stephen’s death and Henry II’s unopposed accession in 1154. Hence, Option A is correct.
Though the church and the majority of the baronage supported Stephen, Matilda’s claims were powerfully upheld in England by her half brother Robert of Gloucester and her uncle King David I of Scotland.
Simon de Montfort opposed Henry III's rule as a baron. Edward I, also known as Edward Longshanks and the Hammer of the Scots, was King of England from 1272 to 1307 after the death of Henry III. Since none of them became immediate successors to Henry I, these options are incorrect.