_________ ecosystems are maintained artificially by man.

The correct answer is: A. Man-made

Man-made ecosystems are ecosystems that are created by humans. They can be found in a variety of places, including parks, gardens, and farms. Man-made ecosystems are often designed to provide a specific benefit to humans, such as food, recreation, or education.

Man-made ecosystems can be very complex, and they can support a wide variety of plants and animals. However, they are also very fragile, and they can be easily damaged by human activities.

Here is a brief explanation of each option:

• Option B: Marine ecosystems are ecosystems that are found in the ocean. They are characterized by their high salinity and their abundance of marine life. Marine ecosystems are essential to the Earth’s climate and to the global food chain.
• Option C: Artificial ecosystems are ecosystems that are created by humans. They can be found in a variety of places, including parks, gardens, and farms. Artificial ecosystems are often designed to provide a specific benefit to humans, such as food, recreation, or education.
• Option D: Brackish ecosystems are ecosystems that are found in areas where fresh water and salt water mix. They are characterized by their high salinity and their abundance of brackish water plants and animals. Brackish ecosystems are found in estuaries, lagoons, and other coastal areas.