In modulation, FM utilizes what kind of variations compared to AM?

In modulation, frequency modulation (FM) employs variations in frequency to encode information, which is the key distinction from amplitude modulation (AM). In FM, the frequency of the carrier wave is altered in accordance with the amplitude of the incoming audio signal. This means that as the audio input changes, the frequency of the carrier wave shifts correspondingly, allowing for the transmission of audio signals with less susceptibility to noise and interference compared to other modulation types.

The other options focus on different aspects of signal modulation. Amplitude variations directly relate to how AM functions, where the carrier wave's amplitude changes with the audio signal. Signal level variations is a somewhat vague term that could be interpreted in various ways, which does not specifically tie it to the fundamental principle of FM. Distance variations aren't relevant in this context as they do not pertain to the modulation methods used in frequency or amplitude changes. Thus, the focus on frequency variations accurately captures the essence of FM modulation.