We are seeking a prime minister who will devote himself to the interest of the country.A

问题补充：

We are seeking a prime minister, who will devote himself to the interest of the country.

A. he

B. him

C. that

D. one

答案：

A. he

B. him

C. that

(答案→)D. one

解析：句意：我们正在寻找一位总理，也就是一位能把自己的一生贡献给国家的利益的人。one是先行词，这里who引导的是定语从句。one在这里是a prime minister的同位语，故选D。