In 1863 the United States government began providing which of the following to mail carriers

A．Anyone who wanted to build railroads could get some land.
B．"Land grant colleges" had land.
C．People moved to the new areas which had became states.
D．There were a lot of family farms after 1862.

A．It was very easy to counterfeit.
B．It increased the cost of mail delivery.
C．It was difficult to affix to letters.
D．It had to be purchased by the sender in advance.