The correct option is B Dark reaction
Dark reaction is the second phase of photosynthesis. It is purely enzymatic and slower than the photochemical reaction (light reaction). It takes place in the stroma region of the chloroplast and is independent of the light. It can occur either in the presence or in the absence of light provided that the assimilatory power is available. During dark reaction, ATP and NADPH (products of light reaction) are utilised to fix carbon dioxide, which is further used to produce carbohydrates.