_____ is our belief that improvements in health care will lead to a stronger, more prosperous economy. [ ]

A. As

B. That

C. This

D. It

患者女性，70岁。反复黑便，呕吐咖啡色液体1月余，消瘦，腹胀，腹部未触及包块，血红蛋白50g／L，白细胞6.6×10⁹／L。

最有效的治疗方法是（）

A.放射治疗

B.分子靶向治疗

C.化学治疗

D.手术治疗

E.生物治疗