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: Pathology
Which of the following fatty acid is a precursor of arachidonic acid? 
Select and explain. 
A. Linoleic acid, B. Linolenic acid, C. Oleic acid, D. Palmitoic acid
A: Linoleic acid
Answer: A: Linoleic acid 
Explanation: Arachidonic acid is a 20-carbon polyunsaturated fatty acid (5,8,11,14-eicosatetraenoic acid) that is derived from dietary sources or by conversion from the essential fatty acid linoleic acid. Ref: Robbins 8th edition, Chapter 2.