Here are the best answers for the questions provided:

1. The athlete **B. broke the world record** celebrated with her team.
2. The book **C. written by J.K.Rowling** became a bestseller.
3. Polly was the only person **B. realized** him.
4. He was the third man **B. was killed** in this way.
5. The girl **D. won the competition** was awarded a scholarship.

So the answers are:
1. B
2. C
3. B
4. B
5. D