What is an essential characteristic of high-pass filters?

High-pass filters are designed specifically to allow high-frequency signals to pass through while attenuating (or rejecting) low-frequency signals. This characteristic is crucial in many applications where it's necessary to eliminate unwanted low-frequency noise or interference while preserving the integrity of higher-frequency signals.

In a high-pass filter, the cutoff frequency determines the point at which the filter begins to attenuate frequencies below a certain threshold. Frequencies above this cutoff will pass through with little to no attenuation, whereas those below the cutoff will be significantly reduced. The ability to reject low frequencies is what makes high-pass filters particularly useful in audio processing, telecommunications, and other signal processing applications where clarity of higher frequencies is desired.

This function is distinct from other options that do not directly describe the purpose of high-pass filters. For example, amplifying all frequencies would not align with the selective nature of filtering, nor would allowing only low frequencies, as high-pass filters are meant to do the opposite. Similarly, while stabilizing voltage levels may be a characteristic of certain circuits, it's not a defining trait of high-pass filters themselves.