How many layers are defined within the US Department of Defense (DoD) TCP/IP Model?

A.
7

B.
5

C.
4

D.
3

Explanation:
The TCP/IP model includes the following four layers: application, host-to-host, Internet, and Network access.
Incorrect Answers:
A: The OSI have seven layers, while the TCP/IP model only has four layers.
B: The TCP/IP model has four layers, not five.
D: The TCP/IP model has four layers, not three.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 518