What is the purpose of a low-pass filter in a broadcast system?

The purpose of a low-pass filter in a broadcast system is to allow signals below a certain frequency to pass while attenuating higher frequencies. This function is essential for various applications, particularly in audio processing and radio communications, where maintaining the integrity of low-frequency signals is crucial.

In a broadcasting context, a low-pass filter effectively removes unwanted high-frequency noise that can distort the intended audio or signal quality. By allowing only frequencies lower than a specified cutoff frequency to transmit, the filter enhances the overall clarity and quality of the broadcast by ensuring that only the desired signals reach the output stage. This capability is particularly important in situations where high-frequency interference might occur, as it helps maintain a clean and well-defined audio signal for listeners.

The other options consider different functions that are not aligned with the primary utility of a low-pass filter. Amplifying signals at all frequencies would not serve the purpose of filtering specific frequencies. Blocking all signals does not facilitate transmission, and combining multiple frequencies into one output describes a function related to mixing or summing rather than filtering. Thus, the role of a low-pass filter is clearly to manage frequency access, making option B the correct answer.