The slaves had a chance to stand up to their owners, since winning the Civil War would mean slavery is abolished. So the slaves had the opportunity to flee to the north where they'd basically be free of slavery and also fight for the union, to help win the war so their people would be freed. However, that's only a number of slaves. There are slaves who still stayed in the south and even helped the confederacy. Due to threats, and caution. In fact, to some slaves, it was their life. All that they know.
If it was a multiple choice question, then under the context of that question the answer is along the lines of "Rise up against owners" or "fight for the union".