The correct answer is the following.
The original thirteen states which were "admitted" between 1787-1790 were the following: Delaware, Pennsylvania, New Jersey, Georgia, Connecticut, Massachusetts, Maryland, South Carolina, New Hampshire, Virginia, New York, North Carolina, and Rhode Island.
The delegates that met at the Constitutional Convention of Philadelphia, Pennsylvania, from May to September 1787, knew they had the difficult task of defining the new dorm of government for the United States after the weak Articles of Confederation. After so many debates, they came up with the US Constitution, after James Madison drafted the Bill of Rights. The next step was the ratification of each state to approve the new COnstitution. And that is how those states became the first 13 admitted.