Final answer:
The correct statement about dark reactions is that carbon dioxide is converted to sugar using ATP and NADPH during the dark reactions, which take place in the stroma of chloroplasts.(Option c)
Step-by-step explanation:
The correct statement about the dark reactions of photosynthesis is: c. Carbon dioxide is converted to sugar using ATP and NADPH during the dark reactions.
Dark reactions, also known as the Calvin cycle or light-independent reactions, take place in the stroma of chloroplasts, not in the thylakoids as suggested in option a. While ATP and NADPH are indeed used in the dark reactions to convert carbon dioxide into sugar, it's important to note that these molecules are produced during the light reactions and not during the dark reactions themselves, which refutes option b. Therefore, the only accurate statement in the choices provided is option c, as it correctly identifies that the dark reactions involve the fixation of carbon dioxide into carbohydrates using the energy from ATP and the reducing power of NADPH, both of which are products of the light reactions of photosynthesis.