I believe the answer is: A. Enslaved people were property and did not have the right to file a suit.
At that time, Dred Scott wanted to sue the government for the mistreatment experienced by his family and demanded that both his wife and kids to be freed from slavery. The court ruled out that only citizens have the right to file a suit and see slaves as property that can never be a citizen.
Answer:
he married Catherine of Aragon
