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
The metabolically most active plasma lipid is: 
Select and explain. 
A. Triacylglycerols, B. Phospholipids, C. Free fatty acids, D. Cholesteryl  esters
C: Free fatty acids
Answer: C: Free fatty acids 
Explanation: Plasma lipids consist of triacylglycerols (16%), phospholipids (30%), cholesterol (14%), and  cholesteryl esters (36%) and a much smaller fraction of unesterified long-chain fatty acids (free fatty acids or FFA) (4%). This latter fraction, the FFA, is metabolically the most active of the plasma lipids.
HARPERS ILLUSTRATED BIOCHEMISTRY30th ed, Page No:254