Posterior column sensations in lower limbs are lost in:

Ans. (B) Vitamin B12 deficiency(Ref: KDT 8/e p654)Deficiency of vitamin B12 leads to megaloblastic anemia which is indistinguishable from folic acid deficiency.Deficiency also have manifestations related to loss of myelin like subacute combined degeneration of spinal cord (symptoms of lesions of posterior column like loss of vibration and proprioception, paranesthesia, depressed stretch reflexes and mental changes like poor memory and hallucinations etc.)