Spirilla bacteria are Gram-negative bacteria that may cause bacterial diarrhea, adenocarcinoma and peptic ulcers.
I believe a river is the answer
Answer:
That would be option D. A motor.
Explanation:
Flagellum. This is the only thing I could come up with because you did not provide an image.
Decaying tree would be considered a biotic as it is now dead, however it will form an ecosystem of bacteria, fungi and other saprotrophs.