Blood in early fetal period is formed in-

Ans. is 'a' i.e., Yolk sac o In early fetal life (upto 10 weeks) erythropoiesis occurs in yolk sac.o By third month of intrauterine life erythropoiesis moves to liver (major) and spleen which are the chief site for erythropoiesis until 5 months of fetal life.o After that erythropoiesis occurs in bone marrow.o In children, blood formation occurs in the marrow cavities of most of the bones. During childhood, there is gradual decrease of erythropoiesis in marrow of long bones and gradual increase in erythropoiesis in marrow of flat bones.o By the age of 20 years, erythropoiesis occurs only in flat bones of axial skeleton (e.g., skull,vertebrae, ribs, sternum and pelvis) and among the long bones, erythropoiesis occurs only in proximal end of femur and humerus.