—Hello! May I speak to Jack please?—A. I’m Jack. B. Is that Jack? C. This is Jack.

问题补充：

—Hello! May I speak to Jack, please?

—

A. I’m Jack. B. Is that Jack? C. This is Jack.

答案：

解析：本题为打电话用语，介绍我是谁通常用this is 来表示，故选C。