Concept:David rebuked Abner for neglecting his duty to guard King Saul while he slept.Explanation:At Ziph, David found Saul sleeping with Abner nearby.He took Saul's spear and water jug to show he could have harmed him.Then David confronted Abner for failing to watch over his master.Thus, Abner did not protect King Saul.Answer:C. failed to protect his master