What is a requirement to enable Cisco IOS IPS with 5.x signature？（）

• A、disable Zone-Based Firewall as the two features are not compatible
• B、disable Cisco Express Forwarding as the two features are not compatible
• C、generate a certificate and export on Cisco.com to receive a signature update
• D、import the public RSA key from the Cisco IPS team that allows the router to verify that a signatureupdate （which was signed by this key） comes from Cisco