The right answer is Lipids.
Just as glucose degradation allows energy production in the cell, in the form of ATP, degradation of fatty acids (lipids) allows cells to obtain the energy necessary for their survival. This degradation occurs in the mitochondria, according to a set of reactions grouped under the term of Lynen's helix (or beta-oxidation of fatty acids).
The degradation of lipids thus allows the synthesis of a usable energy by the cell (ATP).