A group of bacteria that accumulate in layers and secrete a protective extracellular material. (Option A)
Explanation:
Biofilm is defined as one or more types of microorganisms collectively grow in different places. Organisms that form the biofilm include protests, fungi, and bacteria.
Dental plaque is an example of a biofilm. It is a known buildup of slimy bacteria that forms on the teeth surface. Biofilm can grow on different surfaces such as animal tissues, plant tissues, minerals, metal, etc.
Allolactose is an example of an inducer, a small molecule that triggers expression of a gene or operon. The lac operon is considered an inducible operon because it is usually turned off (repressed), but can be turned on in the presence of the inducer allolactose.