This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Pathology
[{'content': 'Megaloblastic anemia is caused by \nSelect and explain. \nA. B6, B. Thiamine, C. Folic acid, D. Riboflavin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C. i.e. (Folic acid) (377- Harsh Mohan 5th) (437- Basic pathology 8th)MEGALO BLASTIC ANEMIAS - two principal causes1. Folate deficiency (Folic acid metabolism)2. Vitamin B12 deficiency* Earliest change in PBS is appearance of hypersegmented neutrophils*** Bone marrow is markedly hypercellular* Macrocytosis (other causes - Haemolysis, liver disease, alcoholism, hypothyroidism**, aplastic anaemia, myeloproliferative disorders and reticulocytosis)* ** MCV |, MCH|, MCHC Normal or |* **SHILLING TEST for Vitamin Bj2 deficiency* FIGLU TEST for folate deficiency* The gene responsible for folic acid transport is situated on chromosome 21**', 'role': 'assistant'}]