What is the correct sequence of structural genes in the $lac$ operon?

How is gene expression regulated in eukaryotes?

Genes that are involved in turning on or off the transcription of a set of structural genes are called:

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 $:-$

Which of the following is true for the $Trp$ operon?

In the $lac$ operon,which of the following acts as an inducer?