Answer
(a) greater than
(b) III
Work Step by Step
(a) At high frequencies, the value of capacitive reactance $X_c$ becomes less and as a result the effective impedance of the circuit decreases, so we have greater current flow.
On the other hand, at low frequencies, the reactance of the capacitor $X_C$ is high and it breaks the circuit. Thus, we have less current flow. We conclude that the current at higher frequencies is greater than the current at lower frequency.
(b) We know that the best explanation is option (III) -- that is, more current flows at high frequency because in that limit the capacitor is like a short circuit and current has two parallel paths to flow through.
