Which fatty acid is not synthesized by man
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.
Linoleic acid
Stearic acid
Palmitic acid
Oleic acid