Question

carbohydrates are composed of which three elements?
a. oxygen, sulfur, and phosphorus
b. carbon, nitrogen, and phosphorus
c. oxygen, hydrogen, and nitrogen
d. carbon, hydrogen, and oxygen

Explanation:

Carbohydrates are organic compounds with the general formula $C_x(H_2O)_y$, so they are composed of carbon, hydrogen, and oxygen.

Answer:

D. carbon, hydrogen, and oxygen