The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Progenitor hematopoietic stem cells originate in   (A) Bone marrow   (B) Thymus   (C) Lymph Node   (D) Spleen
['(A) Bone marrow <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Bone marrow \n (B) Thymus \n (C) Lymph Node \n (D) Spleen <> possible answers', '  Progenitor hematopoietic stem cells originate in <> context@']