题目内容：
根据下列文章,请回答题。Pushbike DangerLow speed bicycle crashes can badly injure -- or even kill -- children if they fall onto the ends of the handlebars (车把). So a team of engineers is redesigning it to make it safer.Kristy Arbogast, a bioengineer at the Children's Hospital of Philadelphia in Pennsylvania, began the project with her colleagues. The cases they reviewed about serious abdominal (腹部的) injuries in children in the past 30 years showed that more than a third were caused by bicycle accidents. "The task was to identify how the injuries occurred and come up with some countermeasures," she says.
By interviewing the children and their parents, Arbogast and her team were able to reconstruct many of the accidents and identified a common cause for serious injuries. They discovered that most cases occur when children hit an obstacle at slow speed, causing them to topple (摇摆) over. To maintain their balance the children turn the handlebars through 90 degrees －－ but their momentum (冲力) forces them into the end of the handlebars. The bike then falls over and the other end of the handlebars hits the ground, pushing it into their abdomen (腹部).
The solution the group came up with is a handgrip (握柄) fitted with a spring and damping (减速) system. The spring absorbs up to 50 per cent of the forces transmitted (传递) through the handlebars in an impact. The group hopes to commercialize the device, which should add only a few dollars to the cost of a bike. "But our task has been one of education because up until now, bicycle manufacturers were unaware of the problem," says Arbogast.The engineers are trying to improve the handlebars because A．they are not beautifu
B．they may kill childre
C．they are likely to cras
D．they affect the speed of the bik
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