Final answer:
The lacZ gene, which encodes β-galactosidase, can be used as a reporter gene to detect the amount of transcription influenced by specific regulatory elements.
Step-by-step explanation:
The correct answer is a) β-galactosidase; Reporter. The lacZ gene encodes β-galactosidase, an enzyme that can be easily measured. The lacZ gene is often used as a reporter gene to detect the amount of transcription that occurs in response to specific regulatory elements. By measuring the levels of β-galactosidase, researchers can determine the level of transcription influenced by regulatory elements.