You have selected the Public Domain Certification. The Public Domain Certification should only be used to certify a work that is already in the public domain. Creative Commons does not recommend you use the Public Domain Certification for dedicating a work still protected by copyright to the public domain. To dedicate a work to the public domain, consider using CC0. Please note that if you use the Public Domain Certification to dedicate a work to the public domain, it may not be valid outside of the United States.
Once you're done filling this out, you will still have the opportunity to confirm your choice before the certification happens.