In a certain low-pass filter, fc = 3.5 kHz. Its passband is____________?
A. 3.5 kHz
B. 0 Hz
C. 0 Hz to 3.5 kHz
D. 7 kHz
A. 3.5 kHz
B. 0 Hz
C. 0 Hz to 3.5 kHz
D. 7 kHz