<prompt> Essential fatty acid -Linoleic acidPalmitoleic acidOleic acidArachidonic acid  <response>: Ans. is a i.e., Linoleic acid o The three polyunsaturatedfatty acids PUFAs, namely, linoleic acidQ linolenic acidQ, and arachidonic acidQ are called essential fatty acids.o They are called essential fatty acids because human beings require these fatty acids but cannot synthesize themQ,o Humans lack the enzymes to introduce double bonds at carbon atom beyond C9 in the fatty acid chain,o Hence, human cannot synthesize linolenic acidQ and linolenic acid having double bonds beyond C9.o Arachidonic acid can be synthesized from linoleic acid.o Therefore, in deficiency of linoleic acid, arachidonic acid also becomes essential fatty acids,o Therefore linoleic acid is the most important essential fatty acidQ as it serves as a basis for the production of other EFA 