I believe the answer is A but i could be wrong, during the Civil war it made it easier for them to speak and talk to each other during that time sending goods and messages across the united states.
Hope this helps.
Answer:
When the cost of the nation's imports exceeds its exports over certain period of time, the situation is called <em>"trade deficit"</em>; during that period from 2000 to 2012 the US National saving decreased and the US Dollar overly flowed out to foreign markets, but foreign investments into US governments bonds increased which also made the country to have large net capital inflow. Thereby the answer would be <em>c)</em><em>:</em>
<em>"The U.S. had a trade deficit and a large net capital inflow."</em>
helped promote exploration, and economic interests
