In the USA conversation is less lively than in many other cultures everyone talks at th

问题补充：

In the USA, conversation is less lively than in many other cultures, everyone talks at the same time.

A which B that C where D what

答案：

解析：考查非限制性定语从句。句意“在美国，与其它文化中的许多人一起交谈相比，会话是不太可能发生的。”cultures指的是有着不同文化的国家，暗指的是地点，且从句不缺少成分。故用where。故选D。