Which of the following would indicate a possible NAT issue affecting an IKEv1 IPsec VPN tunnel?

Which of the following would indicate a possible NAT issue affecting an IKEv1 IPsec VPN tunnel?
A . Phase 1 repeatedly re-establishing
B . Consistent phase 2 negotiation failures
C . ‘No proposal chosen’ error in the event log
D . Continuous ‘NAT detected’ log entries

Answer: D