Q. Last fall I received a letter from the U.S. Office of Personnel Management (OPM), whose records had been hacked, saying my information was included in the intrusion. I don’t know if it’s true. It offered me free identity theft insurance and identity restoration services for three years. When I called for more information, they said I’d have to sign up using my Social Security number, birth date, and all the information I don’t want give out. Do I need to sign up?