听力原文：M: Do you know where Arthur is？
W: I do not know, Paul.
M: He is a fool. And if he did anything I shouldn't mind. But no, he simply can't come away from a game of whist, or else he must see a girl home from the skating-rink and so can't get home.
W: I don't know that it would make it any better if he did something to make us all ashamed.
M: Are you fearfully fond of him, Mum？
W: What do you ask that for？
M: Because they say a woman always likes the youngest best.
W: She may do -- but I don't. No, he wearies me.
M: And you'd actually rather he was good？
W: I'd rather he showed some of a man's common sense.
M: Here is a letter. It's from him.
W: What now !
M: My dearest Mother, I don't know what made me such a fool. I want you to come and fetch me back from here. I came with Jack Bredon yesterday, instead of going to work, and enlisted. Like the idiot you know I am, I came away with him. I have taken the King's shilling, but perhaps if you came for me they would let me go back with you. I don't want to be in the army. My dear mother, I am nothing but a trouble to you. But if you get me out of this, I promise I will have more sense and consideration...
W: Well, now, let him stop!
Arthur is Paul's ______.

A. son
B. father
C. elder brother
D. younger brother