—Can I speak to Mr. Smith, please?

选B。考查情景交际。此处B项为打电话用语, 意为“请稍等”, 符合语境。
【知识拓展】打电话用语
This is. . . (speaking). 我是……(不说I am. . . )
It is. . . here. 我是……
请找……接电话好吗?
Who’s that(speaking/calling)? 你是谁? (不说Who are you? )
Is that. .. (speaking)? 你是……吗?
Is. . . there? ……在吗?
Is. . . in? ……在吗?
Hold on, please. 请稍等。
Hold the line, please. 请稍等。
Can I take a message? 你可以留个口信吗? (对方要找的人不在时)
Can you give/leave a message? 你可以留个口信吗? (对方要找的人不在时)
Can/Could I ask who is calling? 请问您是哪位?
May I have your telephone number? 您的电话号码是多少?