<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 36-year-old woman gravida 5, para 4 was admitted at 31 weeks of gestation with worsening fatigue and shortness of breath on exertion for the past month. She also has nausea and loss of appetite. No significant past medical history. The patient denies any smoking history, alcohol or illicit drug use. Her vital signs include: blood pressure 11060 mm Hg, pulse 120min, respiratory rate 22min and temperature 35.1C 97.0F. A complete blood count reveals a macrocytosis with severe pancytopenia, as follows:Hb 7.2 gdLRBC 3.6 millionuLWBC 4,400mm3Neutrophils 40Lymphocytes 20Platelets 15,000mm3MCV 104 fLReticulocytes 0.9Serum ferritin and vitamin B12 levels were within normal limits. There was an elevated homocysteine level and a normal methylmalonic acid level. Which of the following is the most likely diagnosis in this patient?? A: Vitamin B12 deficiency, B: Iron deficiency anemia, C: Folate deficiency, D: Normal pregnancy, E: Aplastic anemia,  <response>: This is a question about pancytopenia in a pregnant woman. The key findings are macrocytic anemia with severe pancytopenia affecting RBCs, WBCs and platelets. The MCV is elevated at 104 fL, indicating macrocytosis. Reticulocyte count is low at 0.9. Vitamin B12 level is normal, but homocysteine is elevated and methylmalonic acid is normal. This pattern of pancytopenia with macrocytosis and normal B12 levels points to folate deficiency as the most likely diagnosis. Folate deficiency can lead to megaloblastic anemia and pancytopenia. It can occur in pregnancy due to increased folate requirements. The elevated homocysteine and normal methylmalonic acid also support folate deficiency over B12 deficiency. Iron deficiency is unlikely with the macrocytosis. Aplastic anemia would not cause macrocytosis.C: Folate deficiency 