An essential fatty acid is
Arachidonic acid is not one of
the essential fatty acids. Rather it is conditionally essential fatty acid
which, becomes essential if its precursor, linoleic acid is deficient thereby
resulting in the inability to convert linoleic acid to arachidonic acid.
However, some mammals lack the ability or have a very limited capacity to
convert linoleic acid to arachidonic acid, making it an essential part of their
diets. So, the correct answer is 'Arachidonic acid'.