Answer
(a) decreased
(b) decreased
Work Step by Step
(a) We know that the frequency of an ac generator is more than the resonance frequency, so the voltage leads the current. Thus, if we bring the circuit into resonance by changing the frequency of the generator, the frequency should be decreased.
(b) As the frequency of an ac generator is more than the resonance frequency, the inductive reactance $(X_L)$ is more than the capacitative reactance $(X_c)$.
Thus, if we want to bring the circuit into resonance by changing the inductance, the inductive reactance should be decreased, which shows that the inductance of the inductor should be decreased.
