ANS:C - In the liver

Maturation of the immune system starts early in fetal life. Lymphocytes of the B series develop in the liver by 9 weeks' gestation and are present in the blood and spleen by 12 weeks.

Generation of lymphocytes in bone marrow and thymus. The greater part of lymphocyte development in mammals occurs in the specialized environments of the central lymphoid organs"the bone marrow (and the liver in the fetus) for B cells and the thymus for T cells.