challenge: What is notable about the iron bridge in Culford Park, constructed by Samuel Wyatt c.1804?
  
  A. It is the longest cast-iron bridge in the UK
  B. It is one of the earliest bridges with an unmodified cast-iron structure to survive
  C. It was the most expensive bridge built in the 19th century
  D. It was the first bridge to use granite abutments
  Answer: 