Which statement about IKEv2 is true?

Which statement about IKEv2 is true?
A . Both IKEv1 and IKEv2 share the feature of asymmetric authentication.
B . IKEv1 and IKEv2 have enough of the header format in common that both versions can run over the same UDP port.
C . IKEv1 and IKEv2 use same TCP port but run on different UDP ports.
D . IKEv1 and IKEv2 share the concept of phase1 and phase2.

Answer: B