单项选择题

The county is a subdivision of the state usually-but not always-containing two or more townships and several villages. New York City is so large that it is divided into five separate boroughs, each a country in its right: The Bronx, Manhattan, Brooklyn, Queens and Richmond. On the other hand, Arlington County, Virginia, just across the Potomac River from Washington, D.C., is both an urbanized and suburban area, which is not further divided.
Why was com bread called "journey cake"

A.It was easy to ship from England.
B.Horses occasionally ate it if there was no grain available.
C.People took it with them when they traveled.
D.It was easy to prepare over an open fire in the forests.