After Reading the Paragraphs Below, Answer the Questions That Follow

question 3

Multiple Choice

After reading the paragraphs below, answer the questions that follow.
Biosphere II is a huge dome-covered self-contained structure located outside Tucson, Arizona. It was built to try to duplicate Earth's biosphere and ecosystems in miniature and to use the information gained from the experiment to help design similar habitats on the Moon and Mars. The habitat contained small versions of many of Earth's ecosystems, including an ocean with a coral reef, mangrove wetlands, a grassland, a desert, an agricultural system, and a human habitat. Eight men and women were sealed inside the habitat for a proposed two-year stay. The air, water, and food for the "biospherians" all came from inside the sealed habitat, and their only contact with the outside was through computers and telephones.
Before the two years were up, however, the experiment failed. Supplemental oxygen was pumped into the facility, and food supplies were provided through the airlocks. What caused the failure of the experiment? It was traced to nutrient pollution. The soil in some of the biosphere ecosystems was unusually rich in nutrients. These excess nutrients caused a huge population explosion in decomposer bacteria, which led to oxygen depletion.
-To stabilize the environment in the habitat and enable it to become self-sufficient again, it would be helpful to

• A)add nitrates and phosphates to the terrestrial and aquatic ecosystems.
• B)add producers to absorb excess carbon dioxide and produce oxygen.
• C)add consumers to absorb carbon dioxide and produce oxygen.
• D)add decomposers to recycle nutrients in the soil and water.

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Definitions:

Variable Costs

Costs that vary directly with the level of production or volume of output.