Question

Which example is an abiotic factor of an aquarium ecosystem? A. algae growing on the glass B. gravel on the bottom of the aquarium C. plants growing from the gravel D. fish swimming in the water

Answer 1

An abiotic factor is something non-living, doesn't have life-like characteristics. 

Gravel is not life-like. It is not a living thing.

"B" is the best answer.

I hope this helps!
~kaikers

Answer 2

I would say B
hopes this helps