<prompt> Which fatty acid is not synthesized by manLinoleic acidStearic acidPalmitic acidOleic acid  <response>: Linoleic acid Humans lack the enzymes to introduce double bonds at carbon atoms beyond C9 in the fatty acid chain.Hence, humans cannot synthesize linoleic acid and linolenic acid having double bonds beyond C9.It is worth noting that arachidonic acid can be synthesized only if linoleic acid is provided in the diet. 