A、Tourists. B、Motorcyclists. C、Car drivers. D、Walkers. D根据短文第一句For fifteen years，Sustrans—stands for“sustainable transport”—has

For fifteen years, Sustrans -- standing for "sustainable transport" -- has been building traffic-free routes for cyclists and walkers, often through the heart of towns and cities. Several hundred miles are now completed, using disused railway lines, riversides and unused land. As a civil engineering charity, we work in partnership with local authorities and landowners.
    We are now promoting a true national network, composed of traffic-free paths, quiet country roads, on-road cycle lanes and protected crossings.
    Safe cycling networks already exist in many parts of Europe -- including Denmark, Germany, Switzerland and the Netherlands. Europeans are often astonished at the road dangers we put up with here.
    A Danish cyclist is ten times less likely to be killed or seriously injured -- per mile cycled -- than a cyclist in Britain. Extensive national and local cycle routes there are supported by slower traffic systems on surrounding roads.
    A national cycle network for Britain can help transform local transport for the twenty-first century. With your help, it really is achievable! Make a donation now!