Biology

The correct answer is D.Lipid.

Lipids, particularly fats, are the primary biomolecules used for long-term energy storage. They are energy-dense, providing more energy per gram compared to carbohydrates or proteins. Fats are stored in adipose tissue and can be broken down into fatty acids and glycerol to provide energy when needed.

A.Nucleic acids (DNA and RNA) are involved in genetic information storage and protein synthesis, not energy storage.