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
Water soluble vitamins are  not stored in  the  body  in  large quantities except: 
Select and explain. 
A. Vitamin B12, B. Vitamin B1, C. Vitamin B10, D. Vitamin B2
A: Vitamin B12
Answer: A: Vitamin B12 
Explanation: Water soluble vitamins:

Most of these vitamins are readily excreted in urine and they are not toxic to the body. 
Water soluble vitamins are not stored in the body in large quantities (except B12). 
For this reason, they must be continuously supplied in the diet. 
The water soluble vitamins form coenzymes that participate in a variety of biochemical reactions, related to either energy generation or hematopoiesis.
The common symptoms of the deficiency of one or more vitamins involved in energy metabolism include dermatitis, glossitis (red and swollen tongue), cheilitis (rupture at the corners of lips), diarrhea, mental confusion, depression and malaise.
Deficiency of vitamins  B1, B6 and B12 is more closely associated with neurological manifestations 

Key Concept:
Vitamin B12 is the only water soluble vitamin that is stored in the body.
Ref : Textbook of Biochemistry, Satyanarayana