An artificial ecosystem is a man-made ecosystem that is created and maintained by humans. It is designed to mimic natural ecosystems and provide a habitat for different species. Option 1, an aquarium, is an example of an artificial ecosystem. It consists of an enclosed environment, usually a tank or pool, where aquatic plants and animals are kept. The conditions within the tank are carefully controlled to replicate the natural habitat of the species living in it. Option 2, a zoo, is not considered an artificial ecosystem because it typically houses a wide variety of species in separate enclosures, rather than attempting to recreate specific natural environments. Option 3, a sanctuary, and option 4, a national park, are both examples of natural ecosystems that are protected and conserved, but they are not considered artificial.