What effect will increasing the power source frequency have in a capacitive circuit?

Correct Answer: Option C — it will increase the average current in the circuit

Capacitive reactance is inversely proportional to frequency ($X_c = \frac{1}{2\pi f C}$). Increasing the power source frequency decreases capacitive reactance, which consequently increases the overall average alternating current flowing through the circuit in accordance with Ohm's Law.