Final answer:
The light-dependent reactions' main purpose is to transform light energy into chemical energy as ATP and NADPH, which are essential for the light-independent reactions to synthesize carbohydrates.
Step-by-step explanation:
The overall purpose of the light-dependent reactions is to convert light energy into chemical energy in the form of ATP and NADPH. These molecules are then utilized in the light-independent reactions (Calvin cycle) to synthesize carbohydrates from carbon dioxide, a process referred to as carbon dioxide fixation. Moreover, during the light-dependent reactions, oxygen is released as a waste product.
Thus, the statement that best summarizes the purpose of the light-dependent reactions is not just the production of ATP but also the creation of NADPH, and the release of oxygen. All these components are crucial for supporting the photosynthetic process, as they provide the energy and reducing power needed for the subsequent steps of photosynthesis.