When is sugar formed in photosynthesis?

Explanation

The light-independent reactions, also known as the Calvin Cycle, are where sugar formation occurs in photosynthesis. These reactions take place in the stroma of chloroplasts and involve the fixation of carbon dioxide into sugar molecules like glucose, using ATP and NADPH from the light-dependent reactions. The light-dependent reactions do not form sugar directly but provide the energy and reducing power needed for the Calvin Cycle. Therefore, the correct answer is the light-independent reactions, while the other options are incorrect as they either describe processes that do not directly synthesize sugar or incorrectly suggest that sugar is not formed in photosynthesis.