Dred Scott sued for his freedom, arguing that

Athe institution of slavery was immoral and unjust
Bhe had been forced into slavery through illegal means
Che had been a resident of a state where slavery was illegal
Dslavery was a violation of constitutional rights
Ehis owner had abused and tortured him

Verified Answer :

When Dred Scott sued for his freedom, he argued that "(C) he had been a resident of a state where slavery was illegal," since he had resided in the Illinois and Wisconsin territories. The court ruled against him since it was decided he could not claim US citizenship.