Shells are considered biotic because they come from living things. Biotic describes something living or use to be living such as plants and animals. So shells are considered biotic because they come from a living organism.
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The ecosystem will collapse and fail because every species are needed and play a role in the ecosystem.
Symptoms of severe anxiety evident in this case include; confusion, sweating, withdrawal, rapid speech, and a perceptual field that is reduced greatly and distorted. The perceptual field is heightened in mild anxiety while in moderate anxiety, the ability to think clearly is hampered but learning and problem solving can still take place. Additionally in panic, communication is unintelligible or there is an inability to speak.
The answer to the first question is a.