2. 一位22歲的女性患者求診主訴為兩側手關節疼痛及全身倦怠感有半年之久,其間偶而有口腔粘膜潰瘍發生。檢查顯示Hb12.8 g/ml,WBC 3,800/ul,platelet 98000/ul,RF 28 IU/ml,尿液常規正常。請問下列那種檢查對於鑑別診斷最有幫忙?
(A) Bone marrow examination
(B) Serum protein electrophoresis
(C) ANA test
(D) Liver profile
(E) X-ray film of the affected joint