Which of the following is an improper behavior. when taking the phone interview？A．Sipping

Which of the following is an improper behavior. when taking the phone interview？

A．Sipping some water to wet the mouth.

B．Smiling and making their voice sound nice.

C．Speaking slowly and clearly.

D．Answering all the questions without hesitation.

请帮忙给出正确答案和分析，谢谢！