General exam question G8A14

WhyLink margin is the difference between received power level and the minimum required signal level at the input to the receiver. Link margin is the cushion between the power level actually received and the minimum signal level the receiver needs to work reliably, essentially how much room there is before the link starts to fail, answer B. It isn't simply the opposite of fade margin (the two concepts are closely related, not opposites), isn't found by subtracting receiver sensitivity from transmit power alone (that skips the path losses and gains a link budget accounts for), and isn't an arbitrary fixed offset like sensitivity plus 3 dB, so A, C, and D are wrong.