Cisco NX-OS Software supports SNMPv1， SNMPv2c， and SNMPv3. Both SNMPv1 and SNMPv2c use a community-based form of security. SNMPv3 provides secure access to devices by a combination of authenticating and encrypting frames over the network. Which security features are provided in Cisco NX-OS SNMPv3？ （）

• A、 encryption—scrambles the packet contents to prevent them from being seen by unauthorized sources
• B、 password—a password （community string） sent in clear text between a manager and agent for added protection
• C、 authentication—determines that the message is from a valid source
• D、 message integrity—ensures that a packet has not been tampered with while it was in transit 
• E、 user—to determine if user authentication is used instead of community strings