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 was 1 his bike in the neighborhood. Yogi ran 2 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 down 4 . As Horton tried to rise, he 5 the situation was very bad. He couldn't feel his legs.
When Horton was 6 on the ground, Yogi was by his side nervously. Horton said, "Go home, Yogi. Go and get 7 to help. " Horton said the words slowly, again and again. 8 , Yogi refused to leave. But Horton continued asking Yogi to go. Finally, the dog 9 .
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 very 10 . The dog never did that before. So they decided to 11 Yogi to see what happened.
The wait was agony(痛苦) for Horton. When he heard the sound of Yogi, he, 12 his eyes and saw the Tates. They were surprised at Horton's condition and they sent him to the hospital quickly.
13 he has to move in a wheelchair (轮椅) now, Horton feels better. Horton says that Yogi and he are much closer after the 14 . "I'm very thankful to Yogi. He played a very 15 role in saving my life. He's my watchdog and my hero," Horton says.
