通读下面短文，掌握其大意，然后在各题所给的四个选项(A、B、C和D)中选出一个最佳选项。
Wherever Paul Horton goes, his six year-old dog Yogi walks closely behind him. They have always been best friends.
One October morning, Horton was1 his bike in the neighborhood. Yogi ran2 beside his master(主人). Yogi had done it every morning for nearly three years. 3 they came to a tall stone edge (边缘), Horton wanted to jump down from his bike. But the wheel hit the stone and Horton fell down4. As Horton tried to rise, he5 the situation was very bad. He couldn't feel his legs.
When Horton was6 on the ground, Yogi was by his side nervously. Horton said, "Go home, Yogi. Go and get7 to help. "Horton said the words slowly, again and again. 8, Yogi refused to leave. But Horton continued asking Yogi to go. Finally, the dog9.
That morning, Bruce Tate and Maggie Tate, two of Horton's neighbors, were taking a walk. When they saw Yogi running down the street alone, they thought it was very10. The dog never did that before. So they decided to11 Yogi to see what happened.
The wait was agony (痛苦) for Horton. When he heard the sound of Yogi, he12 his eyes and saw the Tates. They were surprised at Horton's condition and they sent him to the hospital quickly.
13he has to move in a wheelchair (轮椅) now, Horton feels better. Horton says that Yogi and he are much closer after the14. "I'm very thankful to Yogi. He played a very15 role in saving my life. He's my watchdog and my hero," Horton says.
