<prompt> Which of the following is a polyunsaturated fatty acid?Palmitic acidStearic acidOleic acidLinoleic acid  <response>: Three polyunsaturated fatty acids, linoleic acid, linolenic acid and arachidonic acid are called essential fatty acids EFA. They cannot be synthesised in the body and must be provided in the diet. Lack of EFA in the diet can produce growth retardation and other deficiency manifestation symptoms.Ref: Textbook of Medical Biochemistry, Eighth Edition, Dr Brig MN Chatterjea, page no: 48 