Which of the following switches off the $lac$ operon?

In the $lac$ operon, what does the term "$lac$" refer to?

Human gene expression is regulated when steroid molecules bind to:

Which of the following enzymes increases the permeability of the bacterial cell to lactose?

Which of the following statements is correct regarding the repressor of the $lac$-operon?

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 $:-$