54.下列藥物以臨床建議劑量單次肌肉注射投予犬，藥效作用時間長短的次序為何？ (A)prednisolone＞betamethasone＞hydrocortisone(B)betamethasone＞prednisolone＞hydrocortisone(C)prednisolone＞hydrocortisone＞betamethasone(D)hydrocortisone＞prednisolone＞betamethasone