(d) : Erucic acid is an unsaturated fatty acid belonging to the oleic acid series, occurring as glycerides in rape seed oil and other vegetable oils. It is the cis -isomer, the trans-isomer being brassidic acid. Erucic acid is used as a binder for oil paints. It is useful in manufacture of emulsions to coat photographic films and papers. Oleic acid is found in various animal and vegetable sources. It is widely used in industries including textile, chemical, medicine, leather, stationary, paper making, etc. Linolenic acids is used in making soaps, emulsifiers and quick-drying oils, in beauty products. It helps in acne reduction, moisture retention, etc. Linoleic aicd is an important fatty acid especially for growth and development of infants. Commercially it is used in margarine, animal feeds, soaps and drugs.