Which letter marks the zone of inhibition?

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.

burning fossil fouls really decrease the carbon in the atmosphere so b