Rafts in cell membrane are rich in which of the following?

Some areas of the cell membrane are especially rich in cholesterol and sphingolipids and have been called rafts. These rafts are probably the precursors of flask-shaped membrane depressions called caveolae (little caves) when their walls become infiltrated with a protein called caveolin that resembles clathrin. There is considerable debate about the functions of rafts and caveolae, with evidence that they are involved in cholesterol regulation and transcytosis. Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 2.