Which of the following is a requirement for a dependable transmitter?

A dependable transmitter must radiate RF energy at sufficient power to ensure that the signal can effectively reach its intended destination without loss or degradation. This is critical because if the power level is too low, the signal may not be able to overcome the background noise, distance attenuation, or interference from other signals. Sufficient power allows the transmitted signal to be strong enough for the receiver to decode the information accurately, ensuring reliable communication.

The other options either introduce unnecessary complexity or misinterpret the requirements for a dependable transmitter. Using a fixed frequency may be suitable for some applications but not a strict requirement for all dependable transmitters. Eliminating all noise in the signal is impractical, as complete eradication of noise is virtually impossible; rather, minimizing it to an acceptable level is the goal. Changing frequency constantly does not contribute to dependability and can lead to instability and confusion in communication, as receivers may not be able to track the changing signal effectively.