Encryption is applicable to all of the following OSI/ISO layers except:

A.
Network layer

B.
Physical layer

C.
Session layer

D.
Data link layer

Explanation:
The Physical Layer describes the physical properties of the various communications
media, as well as the electrical properties and interpretation of the exchanged signals. Ex: this
layer defines the size of Ethernet coaxial cable, the type of BNC connector used, and the
termination method. You cannot encrypt nothing at this layer because its physical, it is not protocol
/ software based. Network, Data link and transport layer supports encryption.