The Reason Modulation Is Used in Electronic Communication Is

Multiple Choice

The reason modulation is used in electronic communication is:

A) Efficient transmission and reception of radio waves are not possible unless extremely large antennas are used.
B) Since all intelligence signals occur at approximately the same frequency, there would be catastrophic interference problems if these frequencies were used.
C) Audio frequency radio waves do not propagate long distances very reliably
D) All of the above