阅读下面四篇材料，然后从各题所给的四个选项中选出一个最佳答案。
When our son Bradley was ten, the new bicycle he had received earlier that year was stolen. Owning a bicycle was a big deal to our children when they were little. They spent hours and hours, day after day, on their bicycles, riding up and down the footpath, and at the front of the house. We also rode together as a family a lot. Bicycling was a great way to get the kids out of the house and into the fresh air without spending any money.
Bradley had discovered that his bicycle had been stolen from our backyard in Campbelltown, South Australia, when he and his sister went outside for a morning ride. He couldn't believe that someone would do this.
He got a large piece of cardboard, painted a sign begging for the bicycle to be returned, and tied the sign to the letterbox. The following morning, when I went out to collect the mail, I found a white envelope with the magical words, "Buy yourself a new bicycle". There was a $100 banknote inside.
We were very touched that someone had the heart to do this, We've never been able to thank the person but we suspect(猜想) that it may have been one of our wonderful neighbors. Bradley painted a big"______!"on the sign and we left it outside for a couple of weeks afterwards, hoping the kind stranger would drive down our street.
A delighted Bradley was able to buy a new bicycle. As the years went on, the bicycles became bigger and more expensive but remained just as important for those family bicycle rides. Now Bradley is 25. Sometimes I miss the days when receiving a bicycle was the best thing in the world to them.
All these years later we are still thankful for the stranger's kindness. We were a young family with three little children and it meant a lot to us. We still talk about it and, even now, wonder who the kind stranger was.
