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.
This is what the branches do -
Executive- Enforces Laws (consists of the President)
Leg. - Makes Laws
Judicial - Determines the Structure of federal jurisdiction
So the answer to your question is, Executive.
I am pretty sure it was republicans
hope this helps:)