What addition to the U. S. Constitution was suggested as a way to win the approval of many of its opponents?

The bill of rights was an addition to the US Constitution as a way to win the approval of many opponents. The opponents of the new system of the federation were concerned over the fact that the federal government would have high power and would kill individual rights. Because of that, they were opposed to the Constitution. With the Bill of Rights, they would win support because people's rights were guaranteed.