Through photosynthesis a simple sugar is produced. where do the carbon atoms come from to produce this sugar molecule? carbonyl groups phosphate groups nadph carbon dioxide

Answer is: carbon dioxide (CO₂).

Plants convert solar energy into the chemical energy of sugars (food).

Solar energy is stored in chemical bonds of sugars (glucose for example).  

The overall balanced photosynthesis reaction:  

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.

In carbon dioxide, carbon has oxidation number +4 and in photosynthesis carbon gain electrons (solar energy), so his oxidation number is lowered (reduced).

Light energy is transformed into chemical energy, that is stored in carbohydrate molecules (glucose), which are synthesized from carbon dioxide and water.  

i believe the answer is true.

you need to have a picture of the atom that way we can answer it