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
Monosaccharide with no Asymmetric Carbon- atom- 
Select and explain. 
A. a) Ribulose, B. b) Erythrulose, C. c) Xylulose, D. d) Dihydroxyacetone
D: d) Dihydroxyacetone
Answer: D: d) Dihydroxyacetone 
Explanation: - CH2OH | C=O | CH2OH