What is the primary function of a band-pass filter?

The primary function of a band-pass filter is to attenuate frequencies outside a specified range while allowing those within a particular middle frequency range to pass through. This is essential in various applications, such as communication systems, where it is important to isolate a specific range of frequencies that carry the intended signal while reducing the impact of undesired frequencies that can introduce noise or interference.

By selectively allowing a band of frequencies to pass and blocking both lower and higher frequencies, a band-pass filter enhances the clarity and integrity of the signal intended for transmission or processing. This makes it particularly useful in audio processing, radio frequency communications, and many other electronic applications.

The other options do not accurately describe the function of a band-pass filter. For example, passing only low frequencies relates to a low-pass filter, while blocking all frequencies refers to a notch filter. Amplifying high frequencies would be the role of a frequency amplifier, not a filter. Thus, option B accurately captures the functionality of a band-pass filter.