Which of the following can cause radio frequency interference?

Radio frequency interference (RFI) can indeed be caused by all of the factors listed. Understanding each of these phenomena clarifies why the all-encompassing choice is correct.

Fundamental overload occurs when a transmitter operates beyond its designed capacity, leading to unintended emissions and excessive signal output that can interfere with nearby electronic devices. This is especially relevant in situations where transmitters are improperly tuned or malfunctioning.

Harmonics are frequencies that are integer multiples of a fundamental frequency. When a transmitter generates the fundamental frequency, these harmonics can also be emitted and can interfere with other communications, especially on frequencies that are multiples of the original signal.

Spurious emissions refer to any unintended frequencies emitted by a device that are not the intended signals. These can be caused by various factors, such as component non-linearity or modulation issues. Spurious emissions can easily disrupt other radio communications by introducing noise at unintended frequencies.

Each of these factors can contribute to the overall problem of radio frequency interference, making the choice that includes all of them the most accurate answer. Recognizing the diverse sources of RFI is key to addressing and mitigating interference in telecommunications.