Why is Tristan reluctant to return home after the war？

Why is Tristan reluctant to return home after the war？
A.He blames himself for not being unable to save Samuel’s life.
B.The outside world appeals to him.
C.He is assigned some other tasks in the army.
D.He is willing to travel around.
正确答案：He blames himself for not being unable to save Samuel’s life.