Is this your...?一般疑问句 — 英语选择题

课间，Tom 在图书角捡到一个书包。他先问 Amy："Is this your schoolbag?" Amy 回答："No, it isn't. My schoolbag is on the desk." 他又问 Peter："Is this your schoolbag?" Peter 回答："Yes, it is. Thank you!" 请判断：这个书包是谁的？根据对话选出正确说法。 A. It is Amy's. B. It is Peter's. C. It is Tom's. D. We don't know.