The following aquariums were set up witht he same volume of water. (Elodea is an awautic green plant.)
aquarium 1: Elodea only
aquarium 2: Elodea and an aquatic snail
aquarium 3: Aquatic snail only
Which aquariums will establish a cycle of carbon dioxide and oxyfen gas flow if placed in the ddark for serveral weeks
A: 1,2, and 3
B: 2 and 3
c: 3 only
d: none