The elders of Israel agreed to make David king over Israel because

The question is asking why the elders of Israel agreed to make David their king. The options are: A) Abner spoke to them, B) Ishboshet was a weakling, C) God had promised to save Israel through David (which is the correct answer), D) David was a great warrior, and E) he had no hand in the death of Saul, Abner, or Ishboshet.

The correct answer is option C. The elders of Israel agreed to make David their king because God had promised to save Israel through him. Throughout the Old Testament, God had promised that the Messiah, who would save Israel, would come from David's line. This promise was fulfilled when Jesus, who was a descendant of David, was born.

David was also a great warrior, as mentioned in option D, but that was not the main reason why the elders made him king. Additionally, options A and E are not correct because Abner's role and David's lack of involvement in the deaths of Saul, Abner, or Ishboshet did not play a significant role in the elders' decision. Option B is also incorrect because Ishboshet's weakness was not the main reason why David was made king.

Understanding the significance of David's role in God's plan for Israel is important for understanding the importance of the lineage of Jesus Christ as the Messiah.