37 下列何者為 B 細胞所特有,在次級免疫促使 B 細胞類別轉換(class switch)和親和力成熟(affinitymaturation)中扮演重要角色? (A)Terminal deoxynucleotidyl transferase(TdT) (B)Activation-induced cytidine deaminase(AID) (C)