What was created to placate anti-federalists after the constitution was ratified?

The correct answer is:

The Bill of Rights.

Explanation:

Opponents to the new Constitution were known as Anti-federalists, although they agreed that a stronger federal government was needed, they feared that the Constitution would give too much power to the federal government and that it could lead to tyranny without a Bill of Rights in it.

During the ratification progress Massachusetts, New York and Virginia argued the Constitution needed a Bill of Rights to protect the sovereignty of the states. So as to ensure ratification of the Constitution, federalist James Madison agreed to write a Bill of Rights that would be added to the Constitution.

The Bill of Rights is written in the first 10 amendments of the United States Constitution and protects the rights and liberties of the American citizens.

c is the correct answer for this question.