Because of biogeochemical cycling,
a. human activity has no effect on elements, chemical compounds, and other forms of matter.
b. living organisms are not limited by any one nutrient.
c. nutrients are circulated throughout the biosphere.
d. many nutrients do not reach toxic concentrations in the biosphere.

Because of biogeochemical cycling, nutrients are circulated throughout the biosphere.
Nutrients and matter are distributed throughout the biosphere, SO it is C.
Human activity does have an effect so it's not A.

The scientific method is a series of steps followed by scientific investigators to answer specific questions about the natural world. it involves making observations, formulating a hypothesis, and conducting scientific experiments.the steps of the scientific method are •observation-the first step of the scientific method involves making an observation about something that interests you•question-once you've made your observation, you must formulate a question about what you have observed. •hypothesis-once you've made your observation, you must formulate a question about what you have observed. •experiment-once you've developed a hypothesis, you must design and conduct an experiment that will test it.•results-the results are where you report what happened in the experiment. •conclusion-the final step of the scientific method is developing a conclusion.i hope that this you : )