Why does darkness affect the light-independent reactions of photosynthesis?
plants stop their daytime activities and rest during the night, much like animals do.
light-independent reactions need more heat energy than nighttime temperatures often provide.
mitochondria produce sugars more effectively in the darkness than chloroplasts do.
light-independent reactions require the energy gathered in the thylakoids.

D. Light-independent reactions require the energy gathered in the thylakoids.

Explanation - Light dependent reaction occurs during day time in the thylakoids of the plant cell. This phase requires sunlight to fix carbon dioxide. This phase liberates ATP and NADPH. The NADPH and ATP is used in the light independent phase.

Light independent phase or Calvin cycle do not require or is independent of light for its action. This process releases carbohydrates. Light independent reaction relies and functions using the products formed in the light dependent reaction.  

the correct answer is D.