ATP molecules required for the synthesis of a glucose molecule in the Benson-Calvin cycle are:

Explanation

The Benson-Calvin cycle, which occurs in the stroma of chloroplasts, is the light-independent phase of photosynthesis. During this cycle, carbon dioxide is fixed into organic molecules, eventually forming glucose. To produce one molecule of glucose, the cycle must turn six times, utilizing 18 ATP and 12 NADPH molecules. Each turn of the cycle fixes one carbon atom, requiring 3 ATP molecules. Therefore, 18 ATP molecules are necessary for the entire process. The other options (36, 12, 38) are incorrect, as they either represent energy needs in different processes or do not meet the specific requirements of the Benson-Calvin cycle.