50.下列何者最常見巨核細胞(megakaryocyte)和血小板(platelet)生成增加？ (A)抗磷脂質症候群(antiphospholipid syndrome) (B)原發性血小板增多症(essential thrombocythemia) (C)再生不良性貧血(aplastic anemia) (D)肝硬化(cirrhosis)