In AM, why is the modulation index kept less than or equal to 1 ?

m > 1, will result in interference between carrier frequency and message frequency, resulting into distortion

m > 1, will result in overlapping of both side bands resulting into loss of information

m > 1, will result in change in phase between carrier signal and message signal

m > 1, indicates amplitude of message signal greater than the amplitude of carrier signal resulting into distortion