单选题 He lost all his money. The only thing he could do was to call his wife for help at this moment.
A．being called B．to be called C．calling D．call

【正确答案】 D
【答案解析】[解析] 结构应用
本句考察的是动词不定式作表语，但因主语中含有do，要省略do。因此选项D为答案。