Which of the Following Combinations Will Produce the Highest Expression

Which of the following combinations will produce the highest expression of ?-galactosidase? Assume crp^- is a complete deletion of CRP (cAMP receptor protein) .

A) crp^- on medium with glucose but no lactose
B) crp^- on medium with lactose but no glucose
C) crp^- on medium with both glucose and lactose
D) crp⁺ on medium with lactose but no glucose
E) crp⁺ on medium with both glucose and lactose