N.C. Gen. Stat. § 48A-13

A parent or guardian, as the case may be, entitled to the physical custody, care, and control of a minor, who enters into a contract of a type described in G.S. 48A-11 shall provide a certified copy of the minor's birth certificate indicating the minor's minority to the other party or parties to the contract and in addition, in the case of a guardian, a certified copy of the court document appointing the person as the minor's legal guardian.