D). Many different experiments are performed and repeated.
Carbon is a reactant in the process of photosynthesis but a product in the process of cellular respiration.
<h3>What is carbon cycle?</h3>
Carbon cycle is the physical cycle of carbon through the Earth’s biosphere, geosphere, hydrosphere and atmosphere.
It is the series of processes by which carbon compounds are interconverted in the environment, that includes such processes as
- photosynthesis
- decomposition
- respiration
- carbonification
Carbon cycle involves the incorporation of carbon dioxide into living tissue by photosynthesis and its return to the atmosphere through respiration, the decay of dead organisms, and the burning of fossil fuels.
Therefore, carbon is present in the atmosphere as a reactant during photosynthesis and as a product during cellular respiration.
Learn more about carbon cycle at: brainly.com/question/1627609
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Its Light because it reacts to photosynthesis