Some mutations can disable genes. what might be the result of such a mutation within the lac i regulatory region of the lac operon?

The lac operon is seen in bacteria, which is a sequence of genes on the mRNA molecule. Lac operon is involved in the digestion of lactose in bacteria.

Explanation:

This is a operon which is switched on when substrate i.e. Lactose is available for digestion. Lac operon produces substances like Beta lactase etc which leads to lactose digestion. But if Lac I is mutated, and lost its function, then the regulatory effect of lac operon is gone. That means cell will produce enzymes to digest lactose even if lactose is absent in the media.

i believe the answer would be b. hope it : )