In $Escherichia \ coli$,$lac$ operon is induced by

The $Lac-Operon$ model was elucidated by

Select two statements out of the four given statements $(i-iv)$ with respect to the $lac$ operon.
$(i)$ Glucose or galactose binds with the repressor and inactivates it.
$(ii)$ In the absence of lactose,the repressor binds with the operator.
$(iii)$ The $Z$-gene codes for permease.
$(iv)$ It was elucidated by Francois Jacob and Jacques Monod.

When does $lac$ operon in $E. coli$ become "switched on"?

Assertion $(A):$ Regulation of $lac$ operon by repressor is referred to as negative regulation.
Reason $(R):$ Repressor protein binds to the operator region and prevents $\text{RNA}$ polymerase from transcribing the operon.

Which organism was used by Beadle and Tatum to propose the one gene-one enzyme hypothesis?