Multiple choice general knowledge Horns, nails and hair are soluble fats insoluble carbohydrates keratin proteins complex lipids Reveal answer Fill a bubble to check yourself C Correct answer Explanation Horns, nails, and hair are all made of keratin, a tough, fibrous structural protein. Keratin is insoluble in water and organic solvents. It is NOT a fat, carbohydrate, or lipid.