Final answer:
A mutation in the operator of the lac operon that prevents the LacI repressor from binding would result in a constitutive expression of the genes in the lac operon.
Step-by-step explanation:
If a mutation in the operator of the lac operon prevents the LacI repressor from binding, it would result in a constitutive expression of the genes in the lac operon. This means that the lac genes would be expressed all the time, regardless of the presence or absence of lactose. The mutation would prevent the repressor from blocking the binding of RNA polymerase to the promoter, allowing transcription of the lac genes to occur continuously.