Answer:
The best advice to give students wishing to set up an aquarium with a naturally balanced ecosystem would be:
(D) Put in a few scavengers such as water snails.
Step-by-step explanation:
A naturally balanced ecosystem in an aquarium involves a delicate balance between plants, animals, and microorganisms. To maintain this balance, it is important to have a few scavengers such as water snails that can help keep the tank clean by feeding on algae and other debris. It is also important to avoid overstocking the tank with too many animals or plants, as this can upset the balance of the ecosystem. Therefore, adding a few scavengers can help to maintain a healthy and balanced ecosystem in the aquarium.