Which of the following is not an example of a communication channel?
a. television
b. internet
c. letters
d. traveling

The correct answers is option D

Explanation:

In Physics, a communication channel is referred to a  physical transmission medium through a  multiplexed medium such as a radio channel, computer networks, telecommunications etc.  

Common form of communication channels are  

•Face-to-Face Communication

•Broadcast Media  

•Mobile Communications  

•Electronic Communications Channels

•Written Communication Methods

a) electrical > light, sound, and thermal< < < <

) the mechanical energy of the firefighter moving.< < < < a) electrical > light, sound, and thermal< < < <

c) both a and b.

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.