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: Gynaecology & Obstetrics
28 year old G3 P2 at 16 weeks gestation reports extreme fatigue and her hemoglobin concentration is 7.5g / dL MCV is markedly elevated and measures 12.4 fL. Her peripheral blood smear is shown below. What is most likely etiolgy 
Select and explain. 
A. Iron deficiency, B. Vitamin B6 deficiency, C. Folic acid deficiency, D. Vitamin B12 deficiency
C: Folic acid deficiency
Answer: C: Folic acid deficiency 
Explanation: During pregnancy, megaloblastic anemia is more due to folic acid deficiency than vitamin B12 deficiency.