Answer:
The correct answer is C. An aquarium with water plants and a snail
Step-by-step explanation:
In an aquarium with water plants and snail the flow of oxygen and carbon dioxide will be continuous because plants are able to do photosynthesis which release the oxygen as the byproduct and this oxygen will be used by snail and snail during respiration release CO2 which will be used by plants in the process of photosynthesis to make food for itself.
Therefore there will be symbiotic relationship between plants and snail because snail provides carbon dioxide to plant and plant provide oxygen to the snail and support their survival. Therefore in this container organism would be able to continuously cycle O2 and CO2. So the right answer is C.