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Its revolutionary ideals no longer had any place . As a result people began to look inward . The music became far more introspective ( it is interesting to note that metal music went through a similar change , albeit about a decade later ) . Ones personal experiences and the way in which one was affected by the world , became the driving force of musical content . This introspection was to give birth to the Emo sub - genre .

What may be the reason for music evolution ?
Select from:
a). Because the people want something different .;
b). Because everything evolves and changes .;
c). Because that 's what the radio stations want .;
d). Because it changes according to popularity .;
b).