Why is a shell considered to be biotic? because it is found in the biosphere because it was alive because it came from something living because it is not living

The correct answer is "because it came from something living".

Explanation:

In biology, a shell is defined as a protective structure of mollusks and crustaceans. A shell is considered to be biotic because it came from something living. Shells are not in fact alive as they are made of calcium carbonate and in some cases α-chitin, two non living materials. However, since mollusks and crustaceans are living beings, shells are considered biotic.