At which site does the repressor bind in the $Lac$ operon?

Human gene expression is regulated when steroid molecules bind to:

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

What effect would you expect if gene expression of the $lac$ operon were completely repressed?

In eukaryotes,the regulation of gene expression could be exerted at $:-$
$(I)$ Transcriptional level (formation of primary transcript)
$(II)$ Processing level (regulation of splicing)
$(III)$ Transport of $\text{mRNA}$ from nucleus to the cytoplasm
$(IV)$ Translational level
Choose the correct order for given statements $:-$

An inactive repressor produced by a regulator gene that does not block the operator site in the tryptophan operon is called: