General exam question G7C12

WhyThe cutoff frequency is the frequency above which a low-pass filter's output power is less than half the input power. A low-pass filter's cutoff frequency is defined as the point above which the filter's output power has fallen to less than half the input power (the -3 dB point), marking the practical edge of the passband, answer C. Notch frequency describes a band-reject filter's rejection point, Neper frequency is a different logarithmic unit not used this way, and rolloff describes how steeply attenuation increases beyond cutoff rather than the cutoff point itself, so A, B, and D are wrong.