Final answer:
The process that uses light energy to assemble carbon dioxide and water into carbohydrates during photosynthesis is known as photosynthesis, where ATP and NADPH produced in light-dependent reactions drive the synthesis of carbohydrates in the Calvin cycle.
Step-by-step explanation:
The process in which light energy is used to fuel the assembly of carbon dioxide and water into carbohydrates is known as photosynthesis. Specifically, during the light-dependent reactions of photosynthesis, energy from the sun is transformed into chemical energy and temporarily stored in ATP and NADPH. These molecules then power the light-independent reactions (Calvin cycle) where carbon dioxide is fixed and carbohydrates, like glucose, are synthesized.
The other options provided relate to different biological processes: gluconeogenesis is the synthesis of glucose from non-carbohydrate precursors, chemiosmosis is a process used to generate ATP in both cellular respiration and photosynthesis, oxidation refers to the loss of electrons or an increase in oxidation state by a molecule, atom, or ion, and fermentation is an anaerobic process where glucose is broken down.