The answer is letter A.
In 1869, six years after the work on the Union Pacific Railroad
began, workers of Central Pacific Railroad from the west and the Union Pacific
Railroad from the east met at the Promontory Summit of the state of Utah. This
was the place where Governor Stanford drove the Golden Spike as a symbolism for
the completion of the transcontinental railroad.
At present, this railroad is responsible for hauling freights
and is operated by 8,500 locomotives that run over 32,000 miles in 23 states
west of Chicago, Illinois, New Orleans, and Louisiana. It is currently the
largest railroad network in the United States serviced by more than 47,000
employees.
