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: Pharmacology
Remission with SSRI or TCA patient again having relapse. There may be deficiency of ? 
Select and explain. 
A. Pyridoxine, B. Cobalamine, C. Ascorbate, D. Retinol
B: Cobalamine
Answer: B: Cobalamine 
Explanation: Ans. is 'b' i.e., Cobalamine "Subjects with vitamin B12 deficiency and depression may present with history of past episodes with spontaneous remission or response to treatment with antidepressants and later recognition or development B1,deficiency"