完形填空阅读下面短文，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。
Bo, a golden retriever, won this year's Dog Hero Award from the Ken L Ration dog food company. Bo acted 1 last June. Bo and his owners, Rob and Laurie Roberts, were going down the Colorado River in a 16-foot boat. The June2 was Bo's first time in a boat.
Laurie Roberts said, “Things were fine 3 a 6-foot wave broke in front of us and filled the boat with water. Another big wave caught us from the back and turned the 4 over.” Rob was thrown clear, but Laurie and Bo were unable to move out 5 the boat. “Every time I tried to 6 , my head hit the boat,” Laurie said. “I hit the bottom of the river several times. I 7 I was drowning(溺水).”
Rob picked up the story, “I reached the land and 8 Laurie,” he said. “I saw Bo swim out from under the overturned boat. Then he 9and dived(下潜). Soon he came back up, pulling Laurie by the hair.” Laurie, who was 10 and breathless, tried to catch Bo. But the dog stayed out of reach as is knowing11of them would drown if Laurie pulled him under.12 Laurie caught Bo's tail. He13her 30 yards to the land. Laurie was cut and bleeding, but she was14.
“If it hadn't been for Bo, 15 wouldn't be here.” Laurie told everyone at the Dog Hero awards dinner.
