This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Prostaglandins are derived from : 
Select and explain. 
A. Coicosteroids, B. Oleic acid, C. Linoleic acid, D. Arachidonic acid
D: Arachidonic acid
Answer: D: Arachidonic acid 
Explanation: Prostaglandins are derived from arachidonic acid through the cyclooxygenase (COX) pathway.Two isoforms of COX have been recognized.COX-1 is expressed constitutively, whereas COX-2 is induced by growth factors, tumor promoters, and proinflammatory cytokines.COX catalyzes oxidative cyclization of arachidonic acid to prostaglandin endoperoxide, which is the immediate precursor of prostaglandins, thromoboxane, and prostacyclin