When a capacitor is connected across an AC source, which of the following statements is true?
A. The capacitor will act as a short circuit for the AC signal, allowing all current to pass through.
B. The capacitor will block the AC signal, preventing any current from flowing.
C. The capacitor will impede the flow of AC current, with the impedance decreasing as the frequency increases.
D. The capacitor will have no effect on the AC signal, behaving as an open circuit.