This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of lipid, Subject name: Biochemistry
To be defined as a ganglioside, a lipid substance isolated from nervous tissue must contain in its structure 
Select and explain. 
A. N-Acetylneuraminic acid (NANA), hexoses, sphingosine, long chain fatty acid, B. NANA, a hexoses, a fatty acid, sphingosine, phosphorylcholine, C. NANA, Phingosine, ethanolamine, D. NANA, hexoses, fatty acid, glycerol
A: N-Acetylneuraminic acid (NANA), hexoses, sphingosine, long chain fatty acid
Answer: A: N-Acetylneuraminic acid (NANA), hexoses, sphingosine, long chain fatty acid 
Explanation: Gangliosides They are formed when ceramide oligo-saccharides have at least one molecule of NANA (N-acetyl neuraminic acid) (sialic acid) attached to them. Ceramide--Glucose--galactose--NANA; this is designated as GM3 (ganglioside M3). Gangliosides contribute to the stability of paranodal junctions and ion channel clusters in myelinated nerve fibers. Autoantibodies to GM1 disrupt lipid rafts, paranodal or nodal structures, and ion channel clusters in peripheral motor nerves.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 82