What is the most likely reason for Grendel returning Unferth to the king's mead-hall after he visits Grendel's cave?

AHe hopes returning the king's son will prevent the soldiers from attacking him again.

BHe wants to prove Unferth wrong in their argument.

CHe wants to fight a fair battle with Unferth; the man was injured.

DHe doesn't want to make the king angrier by killing his son.