Question

If there is s large amount of lactose present, how does bacteria respond?

Answer 1

I think it is B. the gene for beta-galactosidase turns off.

hope that help

Answer 2

In the presence of lactose, the gene for beta-galactosidase is turned on by induction. The RNA polymerase binds to the promoter, in the presence of lactose. Lactose binds to repressor leading to structural changes so that it does not bind to the promoter.  This leads to the production of beta-galactosidase which breaks the bond between glucose and galactose, for utilization of lactose.