Final answer:
The Anti-federalists were the group most responsible for demanding a Bill of Rights before ratifying the Constitution.
Step-by-step explanation:
The group most responsible for demanding a Bill of Rights before they would ratify the Constitution were the Anti-federalists. The Anti-federalists were a group of individuals who opposed the ratification of the Constitution because they believed it lacked sufficient protections for individual liberties. They argued that a Bill of Rights was necessary to safeguard the rights and freedoms of the people.
Learn more about The demand for a Bill of Rights