the answer is a because if the model is based on experimental data it wont be good unless it has been tested.
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Anammox (anaerobic ammonium oxidation), which is a reaction that oxidises ammonium to di-nitrogen gas using nitrite as the electron acceptor under anoxic conditions, was an important discovery in the nitrogen cycle.
Fossils can give information about past environmental conditions by showing the type of animal they belonged to. If a scientist found a whale fossil in a desert, he/she could assume that the desert was once an ocean as whales only live in oceans. If someone found a fossil of a lizard that inhabited trees, in the middle of the ocean, then he/she could assume that the ocean didn't exist at one point and instead, there might have been a forest in it's place.
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