阅读下面短文，从各题所给的A、B、C、D四个选项中选出能填入文章中相应空白处的最佳答案。

    Steve is a middle school student. His school is not far 1 his home. He usually comes home after the school 2 at five. But today Steve 3 doesn't come back at half past six. When he 4 at home at seven, Mom asks him, "5 are you late today, Steve?"

    "My teacher asks you to go to our 6 tomorrow. He wants to have a 7 with you," says Steve.

    "To your school? Why?"

    "Because he asks us a question, and only I 8 the answer," Steve says. "Really? You are 9," Mom is very happy. "What is his question?"

    "His question is 'who split（洒） the milk on my chair? It makes my trousers 10."