The center frequency of a band-pass filter is always equal to the

ANS:D - geometric average of the critical frequencies

The center frequency Fc = (fh + fL)/2 at that time RF system or filter is in resonance mode it gives max output by the filter system in terms of power, voltage and current. Centre frequency is critical in nature with output because power current in maximum finally afterwards at that freq. System RF or filter may go to damage or heating take place component may damage.