To transfer the country?

In the following paragragh, for me, “transfer” seems to be the answer, meaning “change” or “transform”, but I've never seen the similar usage before. Am I correct? Thank you for the help.

Question:

Prior to the Civil War, the railroad had become the dominating factor in the economy of the free North and a powerful influence upon the general welfare of the entire nation. But the railroad had to fight for ascendancy, and during the period of his rise, other forms of transport were helping to ____ the country. Before the railroad boom of the 1850’s water carriers almost monopolized domestic commerce, and of these carriers the oldest and for a long time the most successful were the coastal sailing ships.
(A) build up (B) transfer (C) take over