LIFE SCIENCE

Detailed explanation-1: -A repressor protein binds to a site called on the operator. In this case (and many other cases), the operator is a region of DNA that overlaps with or lies just downstream of the RNA polymerase binding site (promoter). That is, it is in between the promoter and the genes of the operon.

Detailed explanation-2: -The operator is a special DNA sequence located between the promoter sequence and the structural genes that enables repression of the entire lac operon, following binding by the inhibitor (lac i) protein. Expression of the lac operon is, in fact, regulated by the presence of lactose itself.

Detailed explanation-3: -The operator is a DNA sequence present between the promoter region and the first coding gene. This operator region serves as repressor protein binding site; option B is correct.

Detailed explanation-4: -Answer and Explanation: Regulatory proteins bind to small molecules such as regulatory DNA sequences that are responsible for the transcription of an operon. An operon is a unit that is formed from linked genes and oversees regulating other genes that control protein synthesis.