For which of the following emission modes is it important for the receiver to be tuned accurately (within 100 Hz)?

Single Sideband (SSB) is an emission mode where the carrier wave and one sideband are suppressed prior to transmission. To make the audio intelligible again, the receiver must artificially reinsert this missing carrier using a Beat Frequency Oscillator (BFO). Because the receiver is guessing exactly where that missing carrier should be based on your tuning dial, you must tune accurately—usually within 50 to 100 Hz. If you are slightly off-frequency, the voice frequencies will all shift up or down, causing the speaker to sound unnatural or like a cartoon character. Other modes are far more forgiving. AM and FM transmit their own carrier and have wider bandwidths, so slight mistuning is barely noticeable. While mistuning CW (Morse code) changes the tone's pitch, the signal remains perfectly readable, unlike a completely unintelligible mistuned SSB voice signal.