What is the most likely reason for Grendel returning Unferth to the king's mead-hall after he visits Grendel's cave?
a. He hopes returning the king's son will prevent the soldiers from attacking him again.
b. He wants to prove Unferth wrong in their argument.
c. He wants to fight a fair battle with Unferth; the man was injured.
d. He doesn't want to make the king angrier by killing his son.