All of the following are part of an operon except

All of the following are part of an operon except
Option 1 : An operator
Option 2 : An enhancer
Option 3 : Structural genes
Option 4 : A promoter

All of the following are part of an operon except
Option 1 : An operator
Option 2 : An enhancer
Option 3 : Structural genes
Option 4 : A promoter