The importance of the Darby family and the Severn bridge lies in the fact that

The importance of the Darby family and the Severn bridge lies in the fact that
 
  a. they symbolize the ability of large businesses dating from the Middle Ages to create marvels of modern technology.
  b. the bridge was the first to be made of cast iron since Roman times.
  c. they are indicative of the small family-owned businesses that made Industrial Revolution possible in England.
  d. they show how new economic realities connected with the Industrial Revolution destroyed small family companies.
  e. they demonstrate that not all technological innovations were economically viable.