challenge: What was the main goal of the projects developed by British Railways in the mid-1950s?
  
  A. To abandon the use of steam locomotives in favour of diesel locomotives
  B. To decentralize the marshalling of goods wagons and servicing of steam locomotives
  C. To centralise the marshalling of goods wagons and the associated servicing of steam locomotives at smaller regional hubs
  D. To centralise the marshalling of goods wagons and the associated servicing of steam locomotives at the United Kingdom's largest freight hubs
  Answer: 