Carbon is the only possible solution in this question for the reason that the chemical formula for glucose is c6h12o6 (6, 12 and 6 underscore) and carbon dioxide is co2. Both of the chemical formula contains carbon that is why that is the main element.
The only two that apply is Oxygen and Water. The last one would be Carbohydrates.
I think I am the biggest loser in the world
C. no difference in the electronegativity of oxygen and hydrogen
