Which of the following switch off lac operon

In the lac operon, the structural genes are switched off when

Select the two correct statements out of the four $(i-iv)$ given below about lac operon.

$i.$ Glucose or galactose may bind with the repressor and inactivate it.

$ii.$ In the absence of lactose, the repressor binds with the operator region.

$iii.$ The z-gene codes for permease.

$iv.$ This was elucidated by Francois Jacob and Jacque Monod.

It is the expression of y gene in lac-operon

In the lac operon which one is responsible for code of repressor ?

In the lactose operon of Escherichia coli, what is the function of promoter