Which of the following is a member of ω9 family?
Omega Classification of Fatty Acid
In this type of classification position of double bond is counted from the methyl end (ω carbon atom).
Depending on the position of first double bond from the terminal end, the fatty acids are again classified into:

ω3 Series: Alpha Linolenic Acid, Timnodonic Acid, (Eicosapentaenoic Acid), Cervonic Acid (Docosahexaenoic Acid) (DHA)
ω6 Series: Linoleic Acid, Gamma Linolenic Acid (GLA), Arachidonic Acid
ω9 Series: Oleic Acid, Elaidic Acid

Self Assessment and Review of BIOCHEMISTRY ; Rebecca James Purumcheril 4th edition pg no 190
Timnodonic Acid
Cervonic Acid
Oleic Acid
Arachidonic Acid