Triple

Target entity: Anselm Marshal, 6th Earl of Pembroke
Context triple: [Gilbert Marshal, 4th Earl of Pembroke, sibling, Anselm Marshal, 6th Earl of Pembroke]

• A. Anselm Marshal, 6th Earl of Pembroke chosen
  Anselm Marshal, 6th Earl of Pembroke, was a 13th-century Anglo-Norman nobleman and the youngest son of the famed knight William Marshal, whose brief tenure as earl marked the end of the male line of the Marshal dynasty.
• B. William of Egremont
  William of Egremont was a 12th-century Anglo-Scottish nobleman, noted as the son of William fitz Duncan and a claimant to the Earldom of Moray.
• C. Gordon de Blois
  Gordon de Blois was the husband of pioneering American modernist architect Natalie de Blois.
• D. Walter Marshal, 5th Earl of Pembroke
  Walter Marshal, 5th Earl of Pembroke, was a 13th-century Anglo-Norman nobleman and magnate who briefly held the powerful Pembroke earldom as one of the sons and successors of the famed knight William Marshal.
• E. Gilbert de Clare, 1st Earl of Pembroke
  Gilbert de Clare, 1st Earl of Pembroke, was a prominent 12th-century Anglo-Norman nobleman and military leader who played a key role in the Norman consolidation of power in Wales and the Welsh Marches.
• F. None of above.
• G. Unsure - the case is ambiguous/there is not enough information to decide.