Which of the following is considered to be part of the biosphere?
a. a raindrop
b. a grain of sand
c. a rock
d. a flower

The biosphere contains the atmosphere (which contains the air), the lithosphere (the whole earth), and the Hydrosphere (which contain the water). And since the raindrop is part of the Hydrosphere, and the others part of the lithosphere, and since the biosphere extends from the deepest root to the highest mountains, All of the four answers are considered to be part of the biosphere.

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