Click here for information. If the option to have the answers emailed to you isn't available or doesn't work(the email may take a few hours to arrive), contact the iTunes Store staff via the link in that article.
The Three Best Alternatives for Security Questions and Rescue Mail
1. Send Apple an email request at: Apple - Support - iTunes Store - Contact Us.
2. Call Apple Support in your country: Customer Service: Contact Apple support.
A substitute for using the security questions is to use 2-step verification: