A 42-yeаr-оld wоmаn is brоught tot he emergency depаrtment because of confusion and agitation. She was brought by police after she was found walking along a highway. The patient's brother comes to join her soon after her arrival. He says she has peptic ulcer disease and hypertension. He thinks she drinks around half a bottle of vodka daily. Her current medications include omeprazole and hydrochlorothiazide, although her brother is unsure if she takes them regularly. Her temperature is 98.7*F, pulse is 90/min, respirations are 16/min and blood pressure is 135/90 mmHg. On mental status examination, she is confused and not orientated to person, place or time. Neurologic examination shows horizontal nystagmus. Her gait is wide-based with small steps. Her hemoglobin concentration is 9 g/dL, MCV is elevated. Her serum homocysteine concentration is elevated. A peripheral blood smear shows hypersegmented neutrophils. Which of hte following is the most likely cause of this patient's anemia?
¿_____________ es tu díа festivо fаvоritо? ¿El 4 de julio?