Some lac operon mutations allow for beta galactosidase to be expressed constitutively even in the absence of lactose. Which of the following lac genotypes would allow for this constitutive expression?
A) I+ P- O+ Z+ Y+ A+
B) Is P+ O+ Z+ Y+ A+
C) I+ P+ O+ Z+ Y+ A+
D) I+ P+ Oc Z+ Y+ A+
E) I+ P+ O+ Z- Y+ A+
Answer: D
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What will be an ideal response?