Unrestricted submarine warfare is the practice of using submarines to attack and sink all forms of enemy shipping, whether they are military or civilian. It is most closely associated with the First World War when Germany's decision to use USW brought the US into the war and led to their defeat.
In the underground railroad, there were safe places that the slave hid and slept that were called "safe houses" or "stations". The slaves traveled in a couple set of routes with regular paths. The slaves hid and slept in stations during the day and then traveled at night, because the slaves owners were looking for them during the day, so the slaves would be safer if they hid and slept during the day.
Therefore the answer that you are looking for is,
All of the above.
I hope that this has satisfied you.
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No taxation without representation" is a slogan originating during the 1700s that summarized a primary grievance of the American colonists in the Thirteen Colonies, which was one of the major causes of the American Revolution