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
Which of these fatty acids is found exclusively in breast milk 
Select and explain. 
A. Linoleic acid, B. Linolenic acid, C. Palmitic acid, D. Docosahexaenoic acid
D: Docosahexaenoic acid
Answer: D: Docosahexaenoic acid 
Explanation: Docosahexaenoic acid

Up to 5-10% of fatty acids in human milk are polyunsaturated. Most of these are linoleic acid with smaller amounts of linolenic acid.
Docosahexaenoic acid is found in human milk and brain lipids and is required for the development of our nervous system and visual abilities during the first six months of life.
Lack of sufficient docosahexaenoic acid may be associated with impaired mental and visual functioning as well as attention deficit hyperactivity disorder.