Answer:
The correct answer is option D.
Step-by-step explanation:
In the given case, a similar amount of colonies is witnessed in both control as well as the test plate. This concludes that it does not influence the organism, thus, there was no enhancement in the rate of reversion, that is, the number of colonies in the test plate does not get decrease. Thus, the compound in the disc is not mutagenic as there was no increase in the reversion rate.