55.下圖losartan結構中之取代基分別為：  
(A)R1＝tetrazole，R2＝R3＝H
(B)R2＝tetrazole，R1＝R3＝H
(C)R1＝R2＝H，R3＝tetrazole
(D)R1＝H，R2＝R3＝tetrazole