What are the two stages of photosynthesis?

Photosynthesis consists of two primary stages: the light-dependent reactions and the Calvin Cycle (often referred to as the dark reactions, though they do not occur in complete absence of light). The light-dependent reactions take place in the thylakoid membranes of the chloroplasts and require sunlight to convert solar energy into chemical energy in the form of ATP and NADPH while releasing oxygen as a byproduct.

In contrast, the Calvin Cycle occurs in the stroma of the chloroplasts, utilizing the ATP and NADPH produced in the first stage to convert carbon dioxide into glucose through a series of enzymatic reactions. This cycle does not directly require light but depends on the products of the light-dependent reactions.

While the choice of dark reactions and light reactions communicates a similar concept, the terminology in option B specifically clarifies the light-dependent processes and the subsequent Calvin Cycle, making it the more precise and widely accepted description of the photosynthetic pathway. The other options refer to processes unrelated to the stages of photosynthesis, such as oxidation and reduction reactions or respiration and fermentation, which are not components of the photosynthetic reaction itself.