Read this sentence from the text:

The Pony Express was the first rapid transit and the first fast mail line across the continent from the Missouri River to the Pacific Coast.

What does this sentence imply about the period in which the Pony Express developed?:

a. There were no trains that went to the Pacific Coast.
b. There was little need for rapid transit before the war.
c. Previous forms of transit to the West did not include mail.
d. There was little need to cross the continent before the war.