The arabinose operon (ara) provides a particularly interesting example of in that when arabinose is present in the environment, the operon is transcribed.
1. negative control
2. push forward control
3. positive translation
4. positive control
5. reverse transcription

Positive control

Explanation:

An operon is a group of genes that are being controlled by a single promoter. An operon can be either positively controlled or negatively controlled, An operon is said to be positively controlled when an activator stimulates the transcription of the genes of the operon and hence, active expression of the genes takes place. The arabinose operon operates to breakdown and metabolizes arabinose, which is a type of sugar in E.coli. The arabinose operon is active in the presence of arabinose because it is only in the presence of this sugar that the operon needs to be active to break down the product. Therefore, one can say that the presence of arabinose is positively controlling the operon.