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
The immediate precursor of mevalonic acid is 
Select and explain. 
A. Mevalonyl CoA, B. Mevalonyl pyrophosphate, C. Acetoacetyl CoA, D. Beta hydroxy-beta methyglutaryl CoA
D: Beta hydroxy-beta methyglutaryl CoA
Answer: D: Beta hydroxy-beta methyglutaryl CoA 
Explanation: Beta-hydroxy beta-methyl glutaryl CoA (HMG CoA). The reduction of HMG CoA to mevalonate is catalysed by HMG CoA reductase. It is a microsomal (endoplasmic reticulum) enzyme.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 148