Why doesn't this aquarium represent a closed system? A. because light, heat, and air can enter and exit B. because it has plastic plants C. because the water is cold D. because there is more than one kind of fishuired.

A. because light, heat and air can enter and exit.

As the container doesn't have a lid and is made of glass, light, heat and air and enter and exit, so its not a closed system as it is exchanging energy with its external environment.