This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hematology, Subject name: Pediatrics
Hematopoisis in first month of life is 
Select and explain. 
A. Medullary, B. Hepatic, C. Lymphatic, D. Mesoblastic
A: Medullary
Answer: A: Medullary 
Explanation: After bih, and during early childhood, hematopoiesis occurs in the red marrow of the bone. With age, hematopoiesis becomes restricted to the skull, sternum, ribs, veebrae, and pelvis. Yellow marrow, comprised of fat cells, replaces the red marrow and limits its potential for hematopoiesis. Reference: GHAI Essential pediatrics, 8th edition