Distinguish macrocytic and microcytic anemia and give a common cause for each.

• A. Macrocytic: MCV increased due to iron deficiency; Microcytic: MCV decreased due to B12 or folate deficiency.
• B. Macrocytic: MCV decreased due to iron deficiency; Microcytic: MCV increased due to B12 deficiency.
• C. Macrocytic: MCV unchanged; Microcytic: MCV unchanged.
• D. Macrocytic: MCV increased due to B12 or folate deficiency; Microcytic: MCV decreased due to iron deficiency or thalassemia.

Answer: (D)