I'd have to say C is the answer
It is taught in school because it has to do with the world around us and it affected our country.
That would be the southern states. The northern states didn't want slavery, but the southern didn't agree and that's how the civil war started!
Assuming that this is referring to the same list of options that was posted before with this question, the answer is that they have gotten involved with casework for all of the following reasons except "domestic issues"