英语完形填空中的一空3 翻译并解释 谢谢

题目

英语完形填空中的一空3 翻译并解释 谢谢
3.Many people find it relatively easy to communicate on a professional level, ( ) the content of conversation is technical,technological or business oriented,but have difficult in stepping from behind their desks and chatting with superiors,co-workers,clients and customers on a more personal level.
a which b on which c in which d that

答案

B.承接上文的on a professional level意思在专业水平上的回话内容是.