A(n) is the simplest form of lipid; it is a carbon chain, flanked by hydrogens, with an acid group at one end and a methyl group at the other end.

            Fatty Acid is the simplest form of lipid.

Explanation:
                   Fatty acids are in fact carboxylic acids which has long aliphatic chains ranging from 4 carbons to 28 carbons in length. These fatty acids either are saturated or unsaturated. Triglycerides are formed when fatty acids get condense with glycerol. Those triglycerides which contain unsaturated fatty acids exist as Oils and those containing  saturated fatty acids forms Fats.