Which term describes encryption that protects the entire original ip packet's header and payload?

The answer is  tunnel mode encryption.   This describes encryption that protects the entire original ip packet's header and payload.  A tunnel mode encryption protects the internal routing information by encrypting the IP header of the original packet. The original packet is encapsulated by a another set of IP headers. .Additional headers are added to the packet; so the payload MSS is less.

The correct answer is: Tunnel Mode Encryption

Explanation:
Tunnel Mode Encryption is used to encrypt the original IP-packet's header and payload. The encryption is done at the gateways. A gateway is the piece of networking hardware used in telecommunications that allows data to flow from one discrete network to another discrete network. The network consists of the computer. Hence the correct answer is Tunnel Mode Encryption.