Answer:
A. B
Explanation:
"B" as labelled in the above is the zone of inhibition.
The Zone of Inhibition is actually a test which is used to assess antimicrobial activities of a material or solution in relation to an micro-organism as a target. It is also known as Kirby-Bauer Test. It measures the antibiotic resistance and also used to inhibit microbial growth.
At the Point B, microbes can not grow in there; they are inhibited.
In the test, if bacterial strain or any other strain is susceptible to the antimicrobial agent, a zone of inhibition appears. If it shows resistance to that agent, then no zone is evidential.
