What is the relationship between light-dependent reactions and the Calvin cycle?

The relationship between light-dependent reactions and the Calvin cycle is best captured by the correct answer, which states that light-dependent reactions produce the substrates for the Calvin cycle.

In the light-dependent reactions, which take place in the thylakoid membranes of the chloroplasts, light energy is converted into chemical energy in the form of ATP and NADPH. These two molecules are essential for the subsequent phase of photosynthesis known as the Calvin cycle, which occurs in the stroma of the chloroplasts. The Calvin cycle uses the ATP and NADPH generated in the light-dependent reactions to drive the conversion of carbon dioxide into glucose through a series of enzymatic reactions.

This interdependence highlights that the light-dependent reactions are crucial for providing the energy and reducing power necessary for the Calvin cycle to synthesize organic molecules. As a result, the production of ATP and NADPH is an essential prerequisite for the carbon fixation processes that occur in the Calvin cycle.