A 28-year-old female presents to the emergency department with severe fatigue, shortness of breath, and pale skin. Her lab results show hemoglobin of 6.8 g/dL and mean corpuscular volume (MCV) of 75 fL. What is the most likely diagnosis?
Iron deficiency anemia
Vitamin B12 deficiency anemia
Thalassemia
Sickle cell anemia