Which of the following is not a region of transcription unit?

Inducer is not part of the transcription unit. Transcription units in DNA consist of primarily a promoter, a structural gene, and a terminator. An inducer is a molecule or compound that triggers the activation or repression of gene expression. Inducers play a key role in the regulation of gene activity by interacting with regulatory proteins, such as transcription factors or repressors, and influencing their ability to bind to DNA.