Which complication does a NAT introduce in SDP for a SIP call?

Which complication does a NAT introduce in SDP for a SIP call?
A . Additional headers due to NAT encapsulation can cause the packet size to exceed the MT
C . When the client is behind a NAT they may be unable to determine the appropriate offset due to time zones.
D . The IP address specified in the connection data field may be an unrouteable internal address.
E . The encryption keys advertised in the SDP are only valid for clients not behind a NA

Answer: D