On an annual basis, what is the net result of the contributions/removals of co2 from the atmosphere due to global photosynthesis and respiration (both terrestrial and marine)?

3gt/year.

Explanation:

The carbon dioxide is released into the atmosphere by respiration of animals. The burning of fossil fuels, erosion also increases the amount of carbon dioxide in the atmosphere.

The terrestrial and aquatic life release a large amount of carbon dioxide in the atmosphere. Annually, around 3 gt amount of carbon dioxide has been released in the atmosphere.

option c is the correct answer.

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.