One way that regulation is often studied is by examining the effects of mutations. For example, mutations within the parts of the lac operon have been well studied. Which of these mutants would be considered a constitutive mutant?A. a mutation in the promoter for the operon
B. a mutation in the gene for β-galactosidase
C. a mutation in the gene for the repressor
D. a mutation in the gene for β-galactosidase permease