Amplitude modulation in which one complete sideband and a portion of the other are transmitted✓Correct answer
A type of modulation in which one sideband is inverted
Narrow-band FM modulation achieved by filtering one sideband from the audio before frequency modulating the carrier
Spread spectrum modulation achieved by applying FM modulation following single sideband amplitude modulation
Explanation
Vestigial sideband is ordinary amplitude modulation in which one sideband is transmitted in full and only a vestige of the other is kept. It is not a form of sideband inversion, narrowband FM, or spread spectrum.