Answer:
Option (B).
Explanation:
E.coli is a gram negative bacteria as the bacteria cannot take up the gram stain. E.coli is diverse in nature and different strains of E.coli is found in the environment.
E.coli is present in the intestine of humans. The strain of the bacteria is helpful as it helps in the digestion of food. The harmful strain of the E.coli bacteria can cause diarrhea by the contaminated food or water. Hence, the bacteria is beneficial or harmful is depend on the type of strain of the bacteria.
Thus, the correct answer is option (B).
