Escherichia coli strains (I-IV) with mutations in the lac operon were studied for galactosidase activity, followed by measuring its mRNA and protein levels (Graphs). The arrow indicates the time of addition of a compound (namely IPTG) that induces the lac operon. Based on the results, the correct option(s) is(are)

Options

1. AIn strain-I, the lac operon is not regulated and -galactosidase is inactive.
2. BIn strain-II, the lac operon is not regulated and -galactosidase is inactive.
3. CIn strain-IV, the lac operon is not regulated and -galactosidase protein is not produced.
4. DIn strain-III, the lac operon is regulated and -galactosidase is active.