Answer: C. To safeguard American's rights
Step-by-step explanation:
A: Independence was already declared
B. Three branches of government were already established in the constitution without amendments.
C. The Bill of rights mainly composed of civil liberties such as the 1st (Freedom of Speech, Assembly, Religion). This is the correct answer.
D. While law enforcement was touched on somewhat in the 10th amendment, this was not the primary focus of the first 10 amendments (the bill of rights)