Answer: 1 : 2 : 1
Explanation:
Carbohydrates were originally referred to as 'hydrates of carbon' because they contained hydrogen, oxygen and carbon.
Sugars, starches, cellulose, and gums all belong to the class of carbohydrates.
They are represented by the general formula Cx(H2O)y, where x and y must be whole numbers.
Thus, Carbohydrates contain carbon, hydrogen and oxygen in the ratio 1 : 2 : 1