The main issue that caused concern between the federal and state governments in the 1800s was Control over slavery.
<h3>Why was this the main issue?</h3>
In the 1800s, the issue of slavery was very contentious with the federal government being controlled at different times by pro and anti slavery politicians.
They therefore came into conflict with states on the issue of slavery with this eventually culminating into civil war.
In conclusion, option C is correct.
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