Answer:
d. carbohydrates.
Step-by-step explanation:
Sugar-consisting molecules. As a source of energy and energy storage cells employ carbs. The carbohydrates in the cells of an organism are broken down to release the stored energy.
Simple carbohydrates
Composed of one or a few molecules of sugar. Examples of simple carbs are table sugar and fruit sugar.
Complex Carbohydrates
Extra sugar from an organism may be preserved as complex hydrates of carbon. They consist of hundreds of molecules of sugar.