Final Answer:
The main product of the carbon reactions is D. a carbohydrate.
Step-by-step explanation:
The carbon reactions, also known as the Calvin cycle or dark reactions, are part of photosynthesis and take place in the stroma of chloroplasts. During these reactions, carbon dioxide is fixed and converted into glucose or other carbohydrates. The primary goal of these reactions is the synthesis of organic molecules, especially carbohydrates, which serve as energy storage compounds.
Option D, a carbohydrate, correctly identifies the main product of the carbon reactions. The process involves a series of enzymatic steps that utilize the energy obtained from the light reactions (ATP) and the reducing power (NADPH) to convert carbon dioxide into a more complex, energy-rich form—carbohydrates. These carbohydrates can later be used by the plant for energy or as building blocks for various cellular structures.
Option D is the answer.