I always leave things about my son up to himself ______his decision is wrong, for I think he can learn more from failure.

A．in case

B．even if

C．unless

D．until

患者，男性，45岁，体重65kg。结肠癌手术后发生肠瘘3月余，主诉乏力、食欲减退、恶心呕吐。体格检查：明显消瘦，精神萎靡，反应迟钝，腹胀，肠鸣音减弱，腱反射消失。

只有确定以下哪一项时才能开始补钾

A．患者的意识状态

B．肝脏功能

C．食欲

D．尿量

E．胃肠功能