Answer:
Option C, Positive control
Explanation:
This process (as described in question) is termed as positive control of transcription. This is a positive control as it causes up regulation. Up regulation enhances or increases the rate at which an operon transcripts.
This is also known as glucose effect and was first discovered in E.coli. To understand the glucose effect, a graph was plotted which depicted that bacteria utilizes glucose as an energy source till it get exhausted. After exhaustion of glucose, lactose is used for exponential growth
Hence, option C is correct
