题目内容：
"Dad, can you tell me how to get ricn. My dad put down the evening paper. 21do you want to get ncn,son
"Because today Jimmy's mom22up in their new car, and they were going to their beachhouse for the weekend. He23three of his friends,24Mike and I weren't invited. They toldus we weren't invited because we were '25kids(孩子) '. "
"They26?" my dad asked unbelievably.
"Yeah. " I replied in a27voice.
My dad silently28his head,and went to reading the paper. I stood waiting for29.
I30the same public school where the rich people sent their kids. That was because my 31lived on one side of the street. Had I lived on the other side of the street, I would have goneto a32school,with kids from families more like mine.
My dad finally put down the paper. I could33he was thinking.
"Well, son," he began slowly. "If you want to be rich, you have to34to use your head,son," he said, smiling. He really35that.
根据以上内容,回答题.
第21答案是（ ） A．How
B．What
C．When
D．Why
参考答案：
答案解析：