Correct Answer - C
Statement II and IV are true about lac operon . In prokaryotes ,a hypothesis was given in 1961 to explain the protein synthesis regulation . This hypothesis was given by F Jacob and J Monod and for this they were awarded Nobel Prize in 1965 , the hypothesis was known by the name of Operon Model.
The operator gene is the segement of DNA , which exercise a control over transcriptions . in the absence of lactose , the repressor binds with the operator gene.