How do multiple capacitors assist in filtering in AC circuits?

Multiple capacitors assist in filtering in AC circuits by effectively blocking certain frequencies when combined with resistors. This filtering action is crucial in various applications, such as in power supply circuits or audio processing, where it is necessary to separate or diminish unwanted frequencies.

In a filter circuit, capacitors work on the principle of reactance, which varies with frequency. At higher frequencies, capacitors present low impedance, allowing those signals to pass through, while at lower frequencies, they offer high impedance, blocking those signals. When capacitors are paired with resistors, this combination creates a filter that can selectively attenuate or allow certain frequencies. This is fundamental to the design of low-pass, high-pass, band-pass, and band-stop filters, where specific frequency ranges are intended to either be passed or rejected.

The other options do not accurately represent the function of capacitors in filtering. For instance, preventing current from flowing is not a characteristic of filtering; instead, capacitors store and release energy. Allowing all frequencies to pass freely contradicts the concept of selective filtering, and amplifying high-frequency signals is not a role that capacitors play in filtering; rather, amplification is typically accomplished using active components such as operational amplifiers.