Answer:
a) Jar C, b) Jar A
Step-by-step explanation:
a) The amount of CO2 is the highest in jar C because it only contains CO2-producing organisms: mice. A plant in the same jar, like in jar B, would counteract this CO2 production by using it to produce oxygen, which would balance it out.
b) Jar A has the lowest amount of CO2 because the plant is by itself only producing oxygen. There is no life form in jar b that produces CO2.