A 65-Year-Old with Persistent Diarrhea Is Found to Be Severely

A 65-year-old with persistent diarrhea is found to be severely underweight and to have a hematocrit of 26% with mean corpuscular volume of 110 fl. Her peripheral blood smear shows oversized red blood cells with bizarre shapes. What is the most likely cause of her anemia?

A) Iron deficiency due to intestinal blood loss
B) Absence of erythropoietin because of poor nutrition
C) Gastrointestinal cancer
D) Deficiency of folate, and potentially also vitamin B₁₂
E) Aplastic anemia