Which of the following protocols operates at the HIGHEST level of the OSI model?

A.
ICMP

B.
IPSec

C.
SCP

D.
TCP

Explanation:
SCP (Secure Copy) uses SSH (Secure Shell). SSH runs in the application layer (layer 7) of the OSI model.
Incorrect Answers:
A: ICMP (Internet Control Message Protocol) works in the network layer (Layer 3) of the OSI model.
B: IPSec (Internet Protocol Security) works in the network layer (Layer 3) of the OSI model.
D: TCP (Transmission Control Protocol) works in the transport layer (Layer 4) of the OSI model.
http://www.rhyshaden.com/osi.htm
http://en.wikipedia.org/wiki/List_of_network_protocols_%28OSI_model%29
http://en.wikipedia.org/wiki/OSI_model