NEET 2005 Biology question

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 :

• (A)in the presence of glucose, E. coli cells do not utilize lactose
• (B)they cannot transport lactose from the medium into the cell
• (C)the lac operon is constitutively active in these cells
• (D)they cannot synthesize functional β-galactosidaseCorrect