E. coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because -

Question

( A ) They cannot synthesize functional beta galactosidase
( B ) The lac operon is constitutively active in these cells
( C ) They cannot transport lactose from the medium into the cell
( D ) In the presence of glucose, E. coli cells do not utilize lactose