Which is NOT an aspect of field experimentation? ( please help! )

-more accurate
-more control
-conducted in the environment
-less control of variables

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Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.

Sequence how oxygen accumulated in the atmosphere and the effect it had on life by completing the flowchart