Were primarily constructed for profit. railroads turnpikes post offices none of the above

Turnpikes

Explanation:

Turnpikes are highways in which it is necessary to pay a toll fee to your dealership to use them, since they take care of their maintenance and in many cases they built it. The payment is made in the toll controls arranged in the connection branches with other roads or in the trunk of the highway (head tolls).

the monroe doctrine is the best known u.s. policy toward the western hemisphere. buried in a routine annual message delivered to congress by president james monroe in december 1823, the doctrine warns european nations that the united states would not tolerate further colonization or puppet monarchs.