Akey difference between simple sugars and more complex sugars (disaccharides and polysaccharides) is that simple sugars:
a) must undergo some preliminary processing before the energy can be released from their bonds.
b) are made up of one sugar unit or building block.
c) have a particular molecular shape that does not stimulate the sweetness receptors on the tongue.
d) are important sources of fuel for cells.
e) can be broken down into different types of carbohydrate molecules.

B) are made up of one sugar unit or building block.

Explanation:

Carbohydrates, also known as carbohydrates, glycids, glucides, saccharides or sugars, are the most abundant biomolecules in nature, consisting mainly of carbon, hydrogen and oxygen, and may also have nitrogen, phosphorus or sulfur in their composition. They can be classified as simple or complex (disaccharides and polysaccharides).

Disaccharides are made up of a sugar unit or building block. They are composed of two monosaccharide molecules. Examples of Disaccharides are Sucrose composed of (Glucose + Fructose), Lactose composed of (Glucose + Galactose) and Maltose composed of (Glucose + Glucose).

On the other hand, polysaccharides are complex molecules formed by more than 10 monosaccharide units.

i believe the correct answer is d