根据短文理解, 从A、B、C、D四个选项中选择最佳答案填空。
Many years ago there lived two brothers in London. They were both very rich. They had 1 ideas about money. They were quarrelling about what would happen if a poor fellow could 2 a million pound note(钞票). One thought that anyone with such a note would have whatever he wanted; the other thought that it would be 3 for him to get anything with the note. They couldn't agree with each other. So they 4 to make a bet(打赌).
It happened that a young man named Henry was wandering through the street that day, who had come to Britain only by chance. Without home and job, he looked 5 and hungry. Suddenly he saw an apple 6 away by a child. The man was so hungry that he was thinking of 7 it up to eat. Just as he was reaching out his hand, he heard a 8 calling him. He looked up and saw the two 9. They gave him an envelope. They told him not to open it until two o'clock. They said. ‘'Nothing but 10 in it.” Then they left.
的图像恒过定点A，若点A在直线mx+ny+1=0上，且满足mn>0，则
的最小值为（ ）
