The equivalent of a structural gene is

The $Lac-Operon$ model was elucidated by

In $Drosophila$,the set of homeotic genes that control the body plan during organ differentiation is known as.......

$Y$ gene in $lac$ operon is responsible for .....

Select the two correct statements out of the four $(i-iv)$ statements given below about the 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 Jacques Monod.
The correct statements are:

Who provided the clear explanation of the $Lac$ operon?