A 28-year-old male presents with dizziness, fatigue, and pallor for over 2 years. Laboratory tests: RBC 3.0×10<sup>12</sup>/L, Hb 70g/L. Blood smear shows hypochromic RBCs with enlarged central pallor and target cells. MCV, MCH, and MCHC are all below normal. Which of the following anemias is LEAST likely?